Zero

"Even if we Reploids are destined to join the scrap heap when that evolutionary step does come about...We still have to fight...Not only against Mavericks, but against our own destiny as well."

- Zero

"I never cared about justice, and I don't recall ever calling myself a hero. I have always only fought for the people I believe in. I won't hesitate...If an enemy appears in front of me, I will destroy it!"

- Zero

Zero (ゼロ) is one of the three main characters of the Mega Man X (series), the main protagonist of the Mega Man Zero (series), and an important supporting character in the Mega Man ZX (series) as the Biometal Model Z. He is the successor of Bass and the greatest creation of Dr. Albert W. Wily. A high ranking Maverick Hunter in the X series, and a legendary freedom fighter in the Zero series, he's a die hard warrior who doesn't hesitate to take action. However, behind his cold and emotionless attitude lies a wounded soul.

Appearance
Zero prominently sports a red color scheme. In his first appearance, Zero's armor was round for the most part with a red, black and white color scheme and white shoulder guards with a stylized "Z" insignia on his left shoulder. His helmet is horned and features a sharp blue crystal in contrast to his partner, X's smoother red gem. Perhaps his most striking feature is his long blond hair that flowed freely about, making Zero appear fiery in comparison to X's more cool and consistent blue scheme. In Mega Man X2 and beyond, Zero is given slightly heavier, more detailed sharper armor, introducing gold highlights and pauldrons (with a Z usually on the left pauldron to reflect the Z that was on his previously rounded shoulder) in his design. His back contains a recharge pack for the Z-Saber.

Zero's power source is solar energy like X, while his body material is comprised of a Titanium Z alloy, and is equipped with peculiar mechanisms called the Z-Brain (the head lens) and the Z-Heart (the chest lens), which conceal an unknown power.

Due to the artist character designer change for Mega Man Zero, Zero is given a design overhaul specifically for the series. His armor is lighter and more humanoid, and he's given a more streamlined helmet to present a much sleeker look. Unlike his previous form, Zero's arms cannot change into a buster form and instead keeps his weapons holstered around his body. The body Zero has in the Zero series is a brighter red than his original body exhibits. It has some navy blue because he inherits the role of the "Mega Man."

Personality
Prior to becoming a Maverick Hunter, Zero was extremely maniacal and relishes in destruction, due to a programming bug in him during Wily's creation of him. He frequently laughed maniacally and screamed ferally during his fight with Sigma. Outwardly, Zero appears cold and emotionless to others, even towards partners X and Axl. However, it is shown that he has the capacity to care for others. Zero keeps his cool under most circumstances. No matter what his enemies do to him, he is always able to come up with a retort.

In spite of not viewing himself as a hero, Zero has often displayed a tendency to sacrifice himself for the sake of others. He also shows distaste for innocent deaths. This is evidenced in his fighting against Neo Arcadia's ruthless policy against Reploids in the first Mega Man Zero game, as well as the second, in which he personally promised to Harpuia that no more Resistance soldiers would come to harm as long as he was around.

Even though Zero does not openly show it, he, too, seems to long for peace between humans and Reploids. However, he has said that he doesn't have any problems fighting, unlike his more pacifistic friend, X; whether his enemy is a Maverick or a human, he will fight at his best. Another notable trait of his is that, despite his great power, Zero views X as the superior Maverick Hunter and considers him a hero, though he doesn't see himself as such. A prime example of this show of respect was in Zero's ending in Mega Man X6: when the scientist who was performing his sealing process asked what would happen if the world faced another crisis; Zero firmly said that the world is in good hands (X's), even when he's gone.

In the Zero series, his personality remains mostly the same, though with some changes. Given that he's been in stasis, he is ignorant of some matters and confused about others, sometimes to the point he starts doubting or believing that he can't win. This is seen a couple of times. First when Ciel was kidnapped by a Golem and he was battling him with his Buster which was not doing too much damage, was slowly starting to lose hope until X gave him his Z-Saber back or when Dr. Weil told him he was a copy, which made him believe he was not Zero, until X claimed he was indeed Zero, thus somewhat swapping roles with X in where X is the one that encourages him to fight instead of the other way around as it used to be during the X series.

Origin
Zero was created by the late Dr. Albert Wily sometime in the early twenty-first century. Wily alluded to him during Bass's ending in Mega Man: The Power Battle, where he mentioned he was developing a robot that will blow away both Mega Man and Bass. Schematic blueprints of his body were seen during Bass's ending in Mega Man 2: The Power Fighters. Learning from his past mistakes, including the accidental creation of Bassnium and his construction of Bass and King, Wily constructed Zero as a new robot, far more advanced than anything he had ever built before, with a power level far superior to that of Bass or Mega Man. He also presumably began to create the Maverick Virus around this time. Wily even dubbed Zero his "greatest masterpiece". Zero was routinely activated in a semi-conscious state during his construction and Wily spoke with him, mirroring what Dr. Light himself did with X. Wily originally planned to use Zero against both Mega Man and the insolent, rebellious Bass. However, it is unknown if this ever happened. Zero contained a flaw in his cognitive program that made him violent and unwilling to obey instructions. Because of this, Wily decided to seal him in a capsule. Decades later, in the early twenty-second century, he was awakened by a group of Reploids prior to the first Mega Man X game.

When he was first activated, Zero awoke as a Maverick (by the definition of wanting to cause harm to humans), and he destroyed all intruders who had dared to enter Wily's lair. Zero was later cornered by Maverick Hunter Elite, Gamma's Maverick Hunter unit, inside an unknown facility—at the cost of the total loss of said unit, however. Not wanting to get any more comrades endangered by the powerful enigmatic Maverick, then-Hunter Commander Sigma himself challenged Zero in a one-on-one battle. Even though Zero eventually gained the upper hand during the battle, Sigma was able to defeat the red Maverick after the gem on Zero's head began to glow with a 'W' symbol, apparently causing Zero great pain. Sigma punched this crystal, shattering it and defeating Zero. As both Zero and Sigma were in close proximity to the former's capsule when they fought, which contained the Maverick Virus, Sigma and Zero were consequentially infected with the virus. Zero was then brought to Dr. Cain, who analyzed him. After that, he recovered from his battle with Sigma and was placed under Sigma's watch. Zero did not show any more signs of Maverick behavior and was enlisted into the Maverick Hunters' 17th Elite Unit.

The Day of Σ
As part of the 17th Elite Unit, Zero became an excellent Maverick Hunter and was soon ranked A-Class, the highest rank the Maverick Hunters had to offer at that point of time. It was during that time in which he met X for the first time who was also part of the 17th Unit, even though he was only ranked B-Class due to his hesitation on the battlefield. The two became friends and partners and worked together whenever they could. Zero soon became somewhat of a mentor to X.

Soon afterwards, a series of Mechaniloids going berserk occurred in Abel City, the city in which the Hunter Base at that point was located. During the course of the investigation, it was Zero who eventually uncovered the identity of the person responsible for the attacks, which was none other than Sigma himself. Zero realized this after analyzing various locations which were seemly connected to the attacks, and by looking over the bodies of defeated Reploids, which were all taken down with a single blow directed at a weak spot. There had been only a very few number of Reploids with such perfect skills, including Sigma. The blows that the defeated Reploids had taken was caused by a beam saber, and not by range-weapons, which ruled out the previously suspected Vile.

Even though Zero managed to block Sigma's first attack, he was soon overwhelmed by Sigma and was used to goad X into attempting to kill Sigma, which would have killed Zero in the process, to see whether X really could hesitate. Upon seeing that X indeed does hesitate, and to get Zero out of his way, Sigma slashed him with his beam saber and abandoned him while he held X captive, and launched a missile attack on Abel City. Some time later, Zero regained conscious and found X all alone in the facility, heavily damaged. He then brought him back to the Hunter HQ.

Mega Man X/Maverick Hunter X
After Sigma's declaration of Reploid Independence on July 4 21XX (June in the US manual of the original game), dubbed "The Day of Σ", Zero, who at that point was the highest-ranked member of the Hunter organization, became the new leader, and he and a repaired X fought together against Sigma's uprising rebellion. Zero saved X during a Maverick attack at the Central Highway from Vile. In Maverick Hunter X, Zero also responded to Vile's question about why Zero would aid a B-Class Hunter like X by informing Vile that he's nothing more than a Maverick at the present. After that, the two split up, with X's task to slow down the Maverick activities in nearby areas while Zero himself was on recon duty at Sigma's fortress.

They eventually met there and together invaded the fortress. Here, they encountered Vile for a second time. Zero was captured by Vile and imprisoned in a cage (in Maverick Hunter X however, Zero was left unconscious by Vile as bait for X). When X was also defeated by Vile, Zero managed to break free (or regain consciousness, as was the case in Maverick Hunter X) and destroyed Vile's armor by firing a charge shot from point-blank range, which was a successful, yet fatal action. Afterwards, Zero handed his Buster Parts to X (only in case X hadn't obtained the Buster Upgrade from the Dr. Light capsules) and encouraged him to continue to fight before ultimately dying in X's arms (Maverick Hunter X also has Zero remarking on the irony of his actions in saving X leading to his death when he earlier told X not to be so careless ).

Vile Mode
In Vile Mode, included after completing the main game in Maverick Hunter X, Zero's characterization was similar to in the main game, including saving X from Vile. However, instead of chasing Vile off, Zero instead retreats with an injured X. Zero later reappears as the final boss alongside X at Sigma's Palace Stage 3, where he learns with X that Vile is in fact working against Sigma as well as fighting X and Zero. He ends up severely injured by Vile, although he eventually managed to sneak up and grab Vile's leg and pin him before he could deliver the final blow against X, also referring to Vile's earlier rant about X "changing the world" as "maverick talk," also grounding Vile so he'd be caught in X's charge shot. It is unknown if Zero managed to survive the charge shot that critically wounded Vile, or if, like in the main game, Zero also ended up destroyed in a sacrificial effort to help bring Vile down.

Mega Man X2
After Sigma had been defeated, the Hunters tried to salvage whatever remained of Zero from the sunken fortress and found Zero's control chip (which serves as Zero's "brain" and consciousness) which had miraculously survived the destruction of the body. However, the Hunters were incapable of creating a new body for Zero because they were unable to analyze his unique body structure.

Six months later, a group of three Mavericks, calling themselves the "X-Hunters" (Counter Hunters in Japan), contacted the Maverick Hunters and claimed to be in possession of all of the rest of the parts that would be required to rebuild Zero. Although the American translation of the game fails to reveal how the X-Hunters gained the parts, the Japanese version elaborates with the claim that Serges built them. The X-Hunters challenged X to a battle in order to win Zero's parts.

When Serges (Sagesse in Japan) constructed the parts for Zero, he upgraded the body, including reinforced shoulder plates and Z-Saber. Other enhancements were the improved arm guards (in contrast to the original streamlined ones) and leg joints, with improved mid-air dash thrusters and gold-plated covers, along with thicker and bigger chest armor. Because Serges was able to rebuild Zero with an improved design, it is theorized that Serges is a reincarnation of Dr. Wily, whose mind could have been programmed into the Maverick Virus before it mutated into the Sigma Virus. The first version of Zero was apparently just a prototype, as shown by the second version's outline being shown in Mega Man 2: The Power Fighters.

X, who didn't want his friend to be in the hands of Mavericks, accepted and eventually recovered Zero's head, body and foot parts. Eventually, Zero was reconstructed by Dr. Cain (now completed with his signature Z-Saber and enforced shoulder plates) and assisted X in destroying the base of the resurrected Sigma. Trying to fool X however, Sigma had constructed a doppelgänger of Zero with Black Armor which he claimed to be Zero, however this copy was destroyed by the real Zero. This is the canon ending. In the Japanese version of the game, Sigma mentions just before his death that Zero is the last of "Wi...numbers", giving the first hint that Zero is the last of the "Wily numbers", or advanced robots built by Dr. Wily.

As a non-canon scenario in X2, if X wasn't able to retrieve all of Zero's parts, the X-Hunters would steal any parts X had previously collected from the Hunter Base, as well as Zero's control chip. Zero would then be reconstructed by Sigma as a Maverick and was fought by X prior to his encounter with Sigma. After being defeated, Zero would regain his consciousness and assist in destroying the base. His weakness in this battle is the Speed Burner.

Mega Man Xtreme
Zero played only a minor role in the story of this game. After X managed to escape the digitized version of the Central Highway, Zero would inform him that Mavericks had hacked the Maverick Hunters' Mother Computer, stealing and corrupting data and allowing other Mavericks to run wild everywhere. While X was digitized again and sent back into the Mother Computer to destroy the protection systems that were needed to be taken out to shut the computer down, Zero would handle Maverick attacks in the real world. Also, later during the game, X would be able to find four capsules within the digitized areas, the Zero Scrambles, which allowed him to "summon" Zero to perform an attack or move. However, this was only combat data of Zero and not the real one.

Mega Man X3
Zero only played a minor role during the Doppler incident. He and X defended the Maverick Hunter Base from Dr. Doppler's Maverick forces and saved X from the traitor Mac. Zero would here and there be of help for X as he could summon him once a mission (this marked the first time Zero was playable, but he wasn't able to fight bosses), using his Z-Buster and his Z-Saber. While trespassing Doppler's secret lab, he saved X from a spike room booby-trap with REX-2000.

If Zero was summoned during the second stage of Doppler's lab at a specific point, he fights a mosquito-like Mechaniloid which is destroyed by him, however the Mechaniloid managed to hit Zero in a last resort attack. The crash of the Mechaniloid damaged Zero's power generator which forced him to return to Hunter Base to have repairs done. Because this made him unavailable for the rest of the trip, he would then lend his Z-Saber to X.

Mega Man Xtreme 2
In Xtreme 2, Zero paired up with X to investigate the resurgence of previously retired Mavericks. Technically speaking, this is the first time Zero was able to fight bosses. It also introduced his famous three hit saber combo, as well as his ability to learn special techniques as opposed to weapons. He battled Gareth, partner of Berkana, who was reviving the dead Mavericks. Afterwards, Zero aided X in the final battle against the resurrected Sigma.

Mega Man X4
Zero's first appearance as a fully controllable character with his own story also marked the most tragic point in his life. At the beginning of the game, Zero encountered his creator within his dreams, who ordered him to finally obey his orders and fulfill his destiny by destroying his nemesis. When he awakened from the nightmare (which is implied to have happened before), he was immediately dispatched to the Sky Lagoon colony which had been attacked by Mavericks. Repliforce was also confronted at the scene, claiming to assist the Hunters in evacuating the city; however, both factions didn't trust each other, and, as a request for interrogation was declined, the Great Repliforce War broke out.

When the Repliforce was labeled Maverick after the Sky Lagoon incident, both X and Zero were assigned different missions to gather information about Repliforce's coup and to cut off their support lines. Iris assisted Zero on his missions as being his operator, like during the Erasure incident from Mega Man Xtreme 2. However, Iris herself was part of Repliforce while her brother, Colonel, was Repliforce's second-in-command and therefore an imminent target for the Maverick Hunters. Iris didn't want the two of them to fight, ravished between her care for Zero and her love for her own brother. When the two of them battled in the Ceremony Hall of Repliforce's command center, it was Iris who stopped the two Reploids from terminating each other by begging her own brother to stop since Zero had previously saved her life after the Sky Lagoon had crashed down. Colonel, who had always regarded Zero as a friendly rival, backed off. Zero, on the other hand, stated that someone had to stop Repliforce at all costs, much to Iris' grief.

When Repliforce's coup began, Zero rushed to the space port to stop the ascension of the military troops to the newly constructed space station of Repliforce, Final Weapon. There he battled Colonel, this time not holding anything back, just like his former friend, with Zero being the victor of the fight. After that, he traveled to the Final Weapon where he was, much to his surprise and horror, encountered by Iris, who was blinded by her grief of the loss of her brother and anger for Zero killing him. She had salvaged Colonel's Control Chip from his remains, fusing it with her own programming, thus resulting her body to transform into a massive Ride Armor like combat form which Zero was forced to battle. Even though he didn't mean to, Zero damaged the exterior power core of the structure, resulting in the destruction of the armor. He hurried to Iris' body, however, it was too late to save her. Whispering to Zero that she did all this because she wanted to live in a world for Reploids only, and that he could live in that world too. She died in his arms and Zero, who was totally overthrown by the pain, began questioning his own reasons for fighting and the means of his own existence. Filled with anger, he confronted General, the leader of Repliforce, defeating him in battle. Upon the end of the fight, General realized that someone had taken control over Final Weapon, aiming it at Earth. Zero went to the control facility, only to find Sigma there, who revealed their pasts to him (back when Sigma was still a Maverick Hunter and Zero was first seen as a Maverick).

After Zero had destroyed Sigma and the General had sacrificed his life to make the Final Weapon self-destruct, Zero escaped the destruction in a small spacecraft, thinking about what he had done. He hadn't been able to save anyone he cared about. He had killed his own friend Colonel, the General, and Repliforce with him, who in the end has only been manipulated by Sigma and the Mavericks. Most of all, he lost Iris, who he had cared about for so long. Questioning whether or not Reploids were destined to become Mavericks after all, he returned to Earth.

If the game was played by X, Zero would only appear at the very end of the story, contacting X from Hunter Base upon his return to Earth by spacecraft. X, wondering what would happen if he turned Maverick, asked Zero to take care of him if that would ever happen. Confused, Zero didn't respond to X's request, although he seemingly realized X's seriousness about the topic and the eventual battle between him and his best friend.

Mega Man X5
Zero played a pivotal role in Mega Man X5. The space colony "Eurasia" was set to impact Earth, recently being coated in a large outbreak of the Maverick virus, which would cause catastrophes of unimaginable proportions. In the meantime, X and Zero faced Sigma on Earth and easily defeated him, however, Sigma lost on purpose to spread the Sigma Virus around the world. Due to this, thousands of Maverick Hunters turned Maverick, yet, the fall of the colony posed to be a bigger threat. In order to stop the impact of the Eurasia, X and Zero both would gather several enhancement parts to power up an old energy cannon, known as "Enigma" to destroy the colony before it could devastate the planet. While doing so, Zero noticed his strange reaction towards the Sigma Virus. While others, like X, got hurt by being surrounded by the virus, he himself actually felt energy growing inside himself, multiple infections of Sigma Virus anomalies even turned him invincible for brief period in time. Behind the scenes, Lifesaver informed Hunter General Signas about his concerns regarding Zero, but also that there might have been a chance to develop antibodies from his DNA to cure the Maverick/Sigma Virus. Yet, the accomplishment of the Enigma was rendered priority one.

However, it didn't matter how much the cannon was powered up, complete destruction of the Eurasia was impossible and only delayed the impact (in the game it's possible to destroy Eurasia with only the cannon, but story-wise it didn't work). As a last resort action, a Space Shuttle was readied to be launched and directed right into the colony to have it self-destruct right at the core. The shuttle would be operated by Zero and the operation succeeded, however debris would still rain down on Earth. Zero was later rescued by the Hunters but the peace only lasted for a short time as a new threat arose from the debris of the Eurasia.

A new virus, merged from the virus inside the colony and the Sigma Virus, called the "Zero Virus" by Alia, had begun to effect the impact area. The area flooded by the new virus was strangely deformed and was filled with anomalies that even resembled Zero. Also, strange Mavericks were found in the area, bosses that actually resembled earlier bosses such as the Shadow Devil and Rangda Bangda. The closer X and Zero got to the source of the virus, the higher Zero's viral infection level rose, yet he still isn't showing any Maverick behavior. Not wanting Zero to become a Maverick, X would fight his friend in order to have him brought back to Hunter Base. Eventually, the battle would end in a draw (both using "Soul Body" on each other when the other thought they were winning). Upon seeing X and Zero both being completely exhausted after their battle, Sigma would reveal himself to destroy them. However, Zero managed to prevent this, protecting X and himself and forcing Sigma to retreat.

If the one who would pursue Sigma was Zero, Sigma would reveal to him that he let the colony fall on Earth solely to purify Zero's body with the virus to clear his mind and awaken his true self. Upon defeating his first form, Sigma would also reveal to Zero that he met an "Old Man" which knew a lot about Zero and his past, caring for him like a father and that it was that man's suggestion to flood Zero's body with the Virus to awaken him. After defeating his large battle body form, Sigma would then try to take X, who was still left unconscious at the scene of his battle with Zero, down with him. Zero would take most of the hit, seriously damaging him. The remains of Sigma attacked Zero and X one final time, impaling both of them through the chest area but was then completely destroyed by Zero who gained consciousness briefly and fired a charge shot at him from his buster.

Exhausted and damaged from the battle, Zero finally realized that he was going to die and while in a state between life and death, he began recalling memories of his creator and his true purpose of existence. Yet, his memory circuits began to cease function. After recalling his memories of Iris and apologizing to her, Zero asked X to live for him, bringing peace to the world. After X was saved and repaired by the spirit of Thomas Light, X searched for Zero, but found nothing but his Z-Saber, which he kept in order to honor his fallen friend.

As a non-canon scenario, if the Shuttle Operation was not successful, the large amounts of the Colony Virus, together with the Sigma Virus Zero had already been infected with from Earth, would "awaken" Zero upon crashing on Earth, thus challenging X to a battle. His mind now cleared and caring about nothing but his mission to fight X, Maverick Zero battled X, resulting in a draw. After taking massive damage during the fight, as Sigma revealed himself and prepared to destroy X, Zero regained conscious and he jumped into the line of fire, protecting X with his body. When X destroyed Sigma in this scenario and was damaged badly, Dr. Light would appear to save him, however he made him forget about Zero and would implant a protection inside X's mind so no information about Zero would be accepted.

Originally, Mega Man X5 was supposed to be the final game of the series and Zero getting killed in the course to make way for Inafune's original plot of the Mega Man Zero series. However, Mega Man X6 was produced unbeknown to him and without his approval, and since the plot of X6 involved Zero once again, he had to modify his Mega Man Zero concept in order to not make the story more confusing.

Mega Man X6
In Mega Man X6, the mad scientist Gate began tampering with Zero's data. By studying a piece of Zero's body found in the debris of the Eurasia crash site, Gate created the new Nightmare Virus, a discolored clone of Zero (called "Zero Nightmare"), and the near-invulnerable Reploid, High Max. X, taking the assault on Zero's reputation personally, set out to investigate. Upon destroying the Zero Nightmare, X is reunited with his friend, mysteriously repaired and carrying a brand new Z-Saber. Together, X and Zero set out to defeat Gate and the imperfectly resurrected Sigma.


 * Who exactly repaired Zero was never directly stated. The Dr. Light capsule hologram, denied knowing who repaired him. It should be noted that the reunion between X and Zero had Zero stating that he repaired himself, and hid himself away while he "healed".

Zero's ending in this game helps to mend the storyline between the Mega Man X and Mega Man Zero games. It shows Zero being sealed to remove a component from his body (presumably something having to do with the virus' influence on him, and/or his original murderous persona). This was originally going to show that the X series had ended, but fans loved the series so much, Inafune was forced to continue, making many people believe that this is either a glimpse of the future, or non-canon. However, recently revealed backstory information in the Japanese Mega Man Zero artbook has revealed that this ending is indeed canon, takes place in an unspecified time period beyond the last X series game, and is in fact considered the first of two different times when Zero sealed himself away (the second time being after the Elf Wars, when he sealed himself away once more in the Rockman Zero TELOS drama tracks, and was then finally reawakened in the Zero series).

Alternatively, it is possible to clear Mega Man X6 without ever finding Zero. In this event, cutscenes show that Zero is indeed alive, but X and the other Maverick Hunters never find him. Zero leaves on his own, stating that there's something he needs to take care of. Like the alternate ending to X5, canonically, this ending does not happen.

Mega Man X7
In Mega Man X7, Zero is responsible for the bulk of the Maverick Hunter workload due to the fact that X has recently refused to battle for any reason, due to his doubts about the Hunters' violent methods (Zero seems to have some resentment towards the workload, as indicated when he says, "I can't believe I'm back here again!" in an irritated tone in his introduction). Zero captures a mysterious Reploid, Axl, who has just recently abandoned the vigilante group Red Alert. Axl assists Zero in stopping Red Alert's rampages, and eventually X rejoins them. While fighting alongside Axl, Zero learns from him at least some of the details about Red Alert's downfall. After the battles, Zero has nightmares of X attacking him, out of obsession for eliminating Mavericks (possibly foreshadowing the rise of Copy X in the Zero series).

Mega Man X7 signified a few changes to Zero's gameplay. His Z-Buster was eliminated altogether, and in addition to learning new attacks from defeated Mavericks, Zero can also gain other melee weapons to replace his saber. This tradition would continue through the rest of the Mega Man X series and up to the Mega Man Zero series.

Mega Man X8
Zero continues to work with X and Axl, who is now working with the Maverick Hunters, in dealing with new threats in Mega Man X8. One of the new navigators, a purple-haired girl named Layer, has shown a romantic interest in him; Zero has not returned the emotion however, simply keeping the relationship professional. Zero's memories of the virus incident from Mega Man X5 continue to haunt him, fueling his hatred towards Sigma. Upon confronting him, Sigma confirms that Zero is the original carrier of the Maverick Virus, which was transferred to Sigma prior to the first Mega Man X game (presumably it happened when Sigma shattered Zero's head gem as depicted in Mega Man X4, though the unlockable animation The Day of Σ in the PSP remake of Mega Man X has put a few doubts on this). This information was long-since stated in Japanese sourcebooks, as well as implied as early as Mega Man X4, but was never before made officially available to the public in other regions.

Mega Man X: Command Mission
In the game Mega Man X: Command Mission, Zero is sent along with X and another Reploid, Shadow, to investigate Reploid uprisings in Giga City. Zero is separated from X after Shadow betrays them, and presumed dead, until he reappears some time later and attacks one of the rebelling Reploids in a mechaniloid factory. At this point, Zero joins X, Axl, and a number of other Reploids that X assembled to assist him. With Shadow's betrayal still fresh in his memory, Zero is unwilling to trust X's new friends, and promptly decides to work alone. However, one of the Reploids, Spider, risks his life in Zero's defense. After this, Zero decides to rejoin X's group permanently, although Spider eventually turns on them as well and reveals himself as Colonel Redips. He had hid his true identity from the group by using a replica of Axl's DNA change, hinting toward the possibility that Spider could have actually existed at one point (since Axl needs to take DNA from a Reploid in order to change into it). Zero briefly hesitated when his allies attempted to stop Redips from using the Supra Force metal, presumably out of shock that Spider and Redips were the same and thus he was "badly duped." However, he would recover and, with the others, defeat Great Redips in the end, before returning to Earth in a broken off part of the elevator.

The Elf Wars
At some unknown point, Zero realized that he carried the virus inside him and may even be continuing to spread it all over the world during his missions as a Hunter. Thinking that the world wouldn't be safe as long as he was still active, Zero admitted himself into a research institute in order to get rid of the virus within him that caused Reploids around him to go Maverick. At the same point, a project was started to analyze Zero as it had been revealed previously (during the Eurasia crisis to be exact), that Zero actually reacted positively to the Sigma Virus, and therefore might hold anti-bodies for the infection. Zero was sealed away and brought to a government lab. At some point, Zero's mind was extracted from the body, possibly for security measures in case something would go wrong while researching it.

For an unknown amount of time, Zero's body was studied by government researchers. One of them, an unnamed female ancestor of Ciel, managed to create the "Sigma Antibody Program", a Cyber-elf capable of reverting the devastated programming of infected Mavericks and therefore destroying the virus completely. This Cyber Elf was the Mother Elf.

However, weapon researcher and DNA revival specialist Dr. Weil, who worked in the lab as well, planned a different way of dealing with the Mavericks, and was unsatisfied with the result. Stealing Zero's mindless body and the Mother Elf, Weil started a conflict that would ultimately cost the lives of 90% of all Reploids and 60% of all humans. This four-year-long period of war was later dubbed the "Elf Wars".

Weil, used the Mother Elf (now known as the Dark Elf) and copies of her (known as Baby Elves) to gain control over Reploids all over the planet, ordering them to destroy each other. At the same time, he worked on upgrading Zero's body, manufacturing an exterior armor around him which boosted the body's specs to its limits as well as granting him the ability to control all Reploids at the same time when combined with the Dark Elf. In order to deal with the body's lack of a "soul", he created and implanted a new consciousness for the body which was loyal to him: Omega.

When the Elf Wars were in their fourth and final year, Zero reappeared on the battlefield, given a copy of his old body (It is still unknown who created the body, though it is presumed to be Ciel's ancestor). Zero managed to infiltrate Weil's laboratory and steal the Dark Elf from Weil. He then ordered every Reploid in the Dark Elf's range to turn against Weil. At that point, Omega was released onto the battlefield, along with a few Mechaniloids, to defeat X and Zero and retrieve the Dark Elf. Zero, who by that time had realized Omega was using his original body, defeated him together with X by using the Final Strike, disabling the massive Reploid.

After the war had ended, Zero decided to seal himself away again, this time, forever. Though X tried desperately to stop his friend, the sealing process had already begun when X arrived, and could not be stopped. Before he lost consciousness, Zero told X that, as long as he was still around, the bloody history would repeat itself over and over again. Before the seal was complete, he encouraged X that this was the right way and that he wanted to believe in human kind, just as X believed in them. With these final words, Zero's seal was complete. However, the sealing was also not eternal, and one hundred years later, he would be forced to awaken once again.

Mega Man Zero Official Complete Works bio
The legendary Reploid who fought valiantly and was known as a hero during the Maverick Wars. Though the soul is indeed that of Zero, the body that Ciel found him in was a copy of the original. Zero's original body, which had caused much damage during the Elf Wars, had been sent into space, and is now known as Omega. But Zero's new body, showing at least as much if not more potential than the last, has saved the world twice over from the evil intentions of Omega and Weil, the man controlling him. Zero was last seen in space. His current whereabouts are unknown.

Mega Man Zero
At the beginning of Mega Man Zero, Zero was discovered in suspended animation in an abandoned laboratory by a human scientist named Ciel, who leads a band of Reploid freedom fighters. Ciel used the Cyber-elf Passy to revive Zero, who in turn saved Ciel from the forces of Neo Arcadia that was pursuing her and her comrades. Zero, however, was suffering memory loss due to "hibernation sickness". As it turned out, Neo Arcadia was the government of the world at this time period. Reploids were discriminated against and often deemed Maverick and terminated without justifiable cause. Copy X, a ruthless, conceited weaker clone of the real X, was in charge of this policy. Zero agreed to join Ciel's team in fighting this oppression of Reploids. Zero would then go on to defeat Copy X's 4 Guardians as well as destroying Copy X himself.

After the battle with Copy X, Zero was declared missing by the Resistance, after the Neo Arcadian Core was destroyed. In truth, Zero is traveling in the desert (he apparently survived by jumping off Neo Arcadia Tower, as he was seen unconscious when Cyber-elf X was talking to him), where he spends one year evading the forces of Neo Arcadia before returning for the events of the second game.

Mega Man Zero 2
At the beginning of Mega Man Zero 2, Zero is still traversing the harsh desert, and still hunted by Neo Arcadia. After a one year battle with the Neo Arcadian Forces, Zero finally succumbs to his injuries, and collapses. When he wakes up, he is now in the new Resistance Base, brought there by unknown means (later revealed to be Harpuia's doing), and meets the new members, including a new commander, Elpizo.

Ciel showed Zero her research on energy, the former thinking that it will give Neo Arcadia a reason not to fight them anymore. Zero tried to hold off Elpizo's Operation Righteous Strike long enough for Ciel to finish her research, but in the end Elpizo still continued his plans, and Zero had to rescue him. Although Elpizo survived, he was driven to madness by the defeat, and Zero had to spend the larger half of the game trying to find him.

During the game, Zero also learned of what had happened before his sealing; Sigma and his Mavericks were defeated, but some time after the Elf Wars broke out, Zero himself helped X to end them by defeating and banishing Omega, the most terrifying "Reploid" of the time. Several decades after Zero was sealed, X sacrificed his body to stop the worst Cyber-elf of all, the Dark Elf, leaving him in a more ethereal form. X's body is destroyed and the Dark Elf is released by the now-rogue Resistance commander, Elpizo. Zero defeats Elpizo, but the Dark Elf escapes. She and Zero appear to know each other, and X informs Zero that the Dark Elf was not always known by her current name. Her powers became a threat due to a curse by Dr. Weil, the man who started the Elf Wars, at which point people began calling her the Dark Elf.

Mega Man Zero 3
In Mega Man Zero 3, Zero, Ciel, and the resistance are traveling through a mountain, as while they were trying to locate the Dark Elf (presumably to end her curse), they found another energy signature resembling the Dark Elf located at the mountain. Upon arrival at the origin of the signal, they discover an immense ship. The Neo Arcadians had roped off the ship, so Zero decides to get a closer look by sneaking in. However, upon arrival, Ciel and the rest of the Resistance unit was discovered by the Neo Arcadians. they didn't seem to be killed though, thus confusing Zero. Harpuia then appears and says that he's letting them off the hook, as there's "bigger fish to fry". After Harpuia leaves, and Zero tries to figure out who the Dark Elf is and why she seemed familiar, Zero then hears a monstrous voice calling him. Upon arriving at the interior of the ship, Zero discovers that Fefnir and Leviathan, as well as their entire unit, was soundly defeated by an immense figure: Omega, the Devil "Reploid". Zero then realizes that Omega was the one who called him. They then fight. Zero seems to defeat Omega and cause grievous damage, but then Omega started regenerating the wound. Harpuia then cuts in and is about to deliver the coup de grace when a mysterious man, Doctor Weil, tells Omega that he is to serve Harpuia as an ally. Copy X MK II then appears and announces that he revoked Dr. Weil's exile. Dr. Weil, Copy X, Harpuia, and Omega then depart after some discussion, although not before Weil cryptically remarks that he's interested in how well Zero will do "in that body of his."

After a few missions, Zero and the resistance then learn that Neo Arcadia is planning to launch Omega into Area Z-3079, a human residential area to capture the Dark Elf. Zero then decides to infiltrate the Missile Facility and divert the missile. However, he wasn't able to stop the launch of the missile. Not wanting to just let Neo Arcadia destroy a human population just to acquire the Dark Elf, he boards the missile and infiltrates it to destroy Omega before the missile arrives at its destination. Unfortunately, Dr. Weil had anticipated Zero's actions, so he had placed Crea and Prea on guard duty of Omega's chamber long before the launch. While he may have defeated them, they still bought the Omega Missile enough time to reach it's target. Zero barely escapes the impact of the missile, and wakes up to see Omega absorbing the Dark Elf, and transforming. Harpuia, having been retired from his position of Neo Arcadia's military force, then attacks Omega in a last ditch effort to stop Weil and Omega, and protect humanity, even if it meant going against X. Unfortunately, thanks to Omega's absorbing the Dark Elf, Harpuia's attacks are ineffective at all. Zero manages to save Harpuia and himself at the last second by telling the Resistance to transport them back. Neo Arcadia then contacts the Resistance base, with Copy X saying they'll call a truce under the condition that they hand over the Ciel system. However, Ciel and the Resistance declines, as she doesn't trust them due to them destroying a human settlement just to get the Dark Elf. Their refusal results in an invasion with three units coming from the desert, the forest, and the Antarctic to attack the Resistance Base. Zero manages to take down the invasion, as well as destroying the newly resurrected Hanumachine, Anubis Necromancess, and Blizzack Staggroff. Afterwards, Zero infiltrates the main base of Neo Arcadia to stop the invasions once and for all. Zero then fights against Copy X Mark II after a debate about how things should be done. Afterward the battle, the original X approaches Copy X and reveals that Omega and Dr. Weil had used him to gain more power, and abandoned him. Copy X then attempts to transform into his second form, despite X's warnings about a device implanted into him, and is destroyed as a result. Dr. Weil then announces X's death to Neo Arcadia, claiming it to be the work of the Resistance, and evokes Ordinance 8 in order to become ruler. Zero and X then decide to go their separate ways, although not before X cryptically informed Zero that it "was the heart that matters, not the body."

After a few more missions and collecting data, Zero learns from Ciel that Dr. Weil is planning on re-enacting the Elf Wars. Unfortunately, Dr. Weil and Omega then seize control of Neo Arcadia using the powers of the Dark Elf and Omega. Weil takes control of all the Reploids on the planet once more. X, however, uses his powers to protect the Reploids in the Resistance Base from Weil's control. Zero sets off to stop Weil, tracking him down to his secret laboratory, which incidentally, was close to where Zero was found at the beginning of the series.

Zero is confronted by Omega, and the two do battle. After defeating two of Omega's forms, Zero lands with Omega's remains in the very room which he was sealed in. Weil then reveals that Zero is a fake, and that Omega is in fact the "real" Zero, and Zero's original body breaks out of the shell that was Omega's previous form. Zero, however, still defeats Omega Zero after an intense duel. When Weil attempts to heal Omega of his wounds with the Dark Elf, the remaining 3 Guardians appear and attack Omega. X himself appears alongside the Guardians, and told Zero of Weil's deception: that Omega may be using Zero's original body, but the "fake" Zero still has his real soul.

So, regardless of Omega using his original body, Zero destroys him (presumably) once and for all, but Weil escapes. The Dark Elf, now free of her curse and called Mother Elf once more, roams free. However, X cannot roam in the real world any longer. Before X goes away, he tells an unconscious Zero to always protect peace between Reploids and humans, a promise Zero keeps up to heart in next game.

Mega Man Zero 4
Eight months after the destruction of Omega, Neo Arcadia remained under Weil's control. After Weil began to terminate humans who opposed him, several groups of humans escaped the city that used to be their utopia. When the Resistance received knowledge of this, they immediately dispatched a team to assist and protect the refugees. Zero, along with Ciel and a few other Resistance members, intercepted an assault team of Weil's Variant drones (remodeled Mechaniloid soldiers which had replaced the Pantheons) that attacked a refugee truck caravan. After countering the attack, Zero and Ciel met Neige, a human journalist who tried everything possible to both bring all people safely to their new refuge, Area Zero, and to find out the whole truth about Weil.

The Variant attack, however, was just the beginning. Zero, while investigating Area Zero, encounters Craft and the Einherjar Warriors, who all serve directly under Dr. Weil. Craft tells Zero of Operation Ragnarok, a plan to destroy all inhabitable areas outside Neo Arcadia so no one can escape Dr. Weil's rule. Zero defeats 4 of the Einherjar one by one, and then repels an attack on Area Zero by Craft himself. The latter's objective was to kidnap Neige, who was an old friend of his. Zero rescues Neige from the prison Craft took her to, but not before Neige managed to push a little of her ideals back into her old friend.

When the rest of the Einherjar Warriors are eliminated, Craft revolts against Weil and commandeers the "Ragnarok" space station, threatening to obliterate Neo Arcadia with the station's laser cannon. The Resistance immediately commences the evacuation of the city while Zero storms the space station. Despite his efforts, Zero is too late and Craft opens fire, destroying the city. Zero then engages Craft in combat and defeats him. Mortally wounded, Craft asks Zero why he continues to fight for the humans that feared him and all Reploids. Zero replies that he was obligated by a promise he has made to a friend and their faith in the human race. Realizing what he's done, Craft asks Zero to continue living up to that promise, before shutting down for good.

All is not well, however. A second laser fired from Ragnarok alerted everyone that it was still operational, and that the station is now falling down to Earth. After going through Ragnarok's defenses to reach the core, Zero discovers Weil waiting for him. Having actually survived Ragnarok's laser fire, Weil teleported into the space station after the blast, maneuvering it to crash into Area Zero. After the first of their two battles, the space station is damaged. Ciel pleads for Zero to return to Earth, lest he get stranded due to increasing transporter interference. Seeing Weil still alive, Zero passes the offer to go back and proceeds to finish him off in their second battle, ultimately sacrificing himself as the destruction of Weil's last form causes the station to explode.

Zero's sacrifice opens the eyes of many, finally bringing peace between the Reploids and humans left on Earth. The aftermath, however, leaves his friends grieving at his apparent death (his actual fate remains uncertain), especially Ciel, who is later inspired to pick up his work to create harmony between Reploids and humans.

Vile's Incident: Eden dome, its sin and rebirth

 * Under Construction

This is a special feature from one of the Remastered Tracks Rockman Zero disks.

Mega Man ZX
Zero returns in the Nintendo DS game Mega Man ZX, as Biometal Model Z, which was modeled after him (but seems to also contain some of his data. There is also a possibility of Model Z containing the "soul" of Zero). Omega Zero also appears as an optional boss in Area N-1. Defeating him in Normal or Hard will grant access to a stone artifact which gives the player Model O. Although Biometal Model Z is not usable by itself, it can be combined with Biometal Model X to form Model ZX, the title character.

Zero appears in a flashback scene in Vent's story, where Prairie explains that her sister was a human (obviously referring to Ciel) that defended the Reploids. The scene then shifts to a view of Zero and Ciel looking at an army of Pantheons. Zero is mentioned when (again in Vent's storyline) Prairie explains that Model W is the spirit of Dr. Weil, and that the last time Dr. Weil had appeared, he was stopped by Zero (although the game never addresses Zero by name, simply calling him "a hero").

Mega Man ZX Advent
Model Z, still in Vent/Aile's possession, reappears in Mega Man ZX Advent. After Ouroborous starts falling apart, Model Z decides to take down the enemy Mega Men by himself, and allows Aile/Vent to go rescue Grey/Ashe, who fainted after the battle against Master Albert. Model Z manages to freeze the four Biometals, which freezes the users themselves. The conclusion of the battle is unknown, since Aile/Vent did not mention anything about Model Z during the ending. However, if the player beats hard mode, then a secret ending shows the four enemy Mega Men alive and well, in their MegaMerged form. As of then, Biometal Z's whereabouts are unknown, mirroring Mega Man Zero 4. He is implied alive, as he said before he disappeared "It's not the day to meet my maker," referencing that no matter what, even in death, he continues to live, resurrected in some way or another, always fighting with whoever he is with.

An interesting point in this is the fact that he seemed to die aboard the Ouroborous, made from Model W's, which are made from pieces of the Ragnarok, the space station where Zero appeared to die in Mega Man Zero 4.

Rockman ×over
Zero appears in some Battle Memory.

SNK vs. Capcom: SVC Chaos
Zero (in his Mega Man Zero series form) appears as a hidden playable character in the fighting game SNK vs. Capcom: SVC Chaos. He serves as a mid-boss, and in his story, it appears he travels back in time, as he is the only Reploid in the time frame and Ciel is the only person outside the time frame who is able to communicate with him. After winning a battle with Shin Akuma, Zero is transported to an ethreal-like cloudy area and then Athena appears to him, Zero asks her where is he exactly and she states that he is in Heaven. Zero then tells Athena for her to send him back since he had a mission to accomplish and had no time for this. Athena then engages Zero in a battle to see if he deserved to be returned to his time, which Zero wins and gets sent back to his own time frame where he re-establishes contact with Ciel. Because he appears in a collaboration game between Capcom and SNK, his story is considered non-canon to the Mega Man series. When playing as Zero, a WARNING signal will appear on boss pre-battle introductions, including Shin Akuma and a Zero mirror match itself. Zero uses many of his weapons from Mega Man Zero, including the Triple Rod, Buster Shot and Shield Boomerang. He can also use Cyber Elves in some of his attacks.

He is reprised by Yuuto Kazama as with his Zero series incarnation.

Onimusha Blade Warriors
Zero (in his Zero series appearance) is also a hidden playable character in the fighting game Onimusha Blade Warriors. Yuuto Kazama also reprises his role as Zero in this game as well.

Tatsunoko vs. Capcom: Ultimate All-Stars
Zero (in his Mega Man X series form) is a playable character in the fighting game Tatsunoko vs. Capcom: Ultimate All-Stars. This is the first time in years to feature Zero in his X form since Maverick Hunter X in 2005 as well as the return of the Z-Buster. Zero has been shown to use many of his command arts including Ryuenjin, Hienkyaku, Shippuuga, Sentsuizan, Kuuenzan, Twin Dream (Sougenmu), Rekkoha, Hadangeki and Dark Hold. In a nod to the following series, his powered-up Z-Saber takes its Mega Man Zero shape when he uses his Dark Hold move.
 * In Zero's story mode, he attacks Yami, and apparently defeats him without mercy, but it suddenly springs him back to life. Dr. Wily then appears in Zero's mind and tells him not to give up on the task he gave him.
 * He also makes a brief cameo in PTX-40A's ending as one of the robots in the tournament.
 * Like in the X series, he is reprised by Ryoutarou Okiayu.

Marvel vs. Capcom 3: Fate of Two Worlds
Zero is a playable character in Marvel vs. Capcom 3: Fate of Two Worlds, appearing once more in his X series appearance, with his battle music from Mega Man X2 as his theme music. Needless to say, Zero appears as his Tatsunoko vs. Capcom incarnation with a few modifications: he has all Command Arts from various X games that were in Tatsunoko vs. Capcom such as Ryuenjin, Kuuenzan, Shippuuga, Rekkouha, Sougenmu, Hadangeki, Sentsuizan, and Hienkyaku. New moves include Raikousen from Mega Man X8 and a powerful wave slash attack known as Genmu Zero (Genmurei), which is his final attack as a boss in Mega Man X5. Other than that, not much else has changed other than his normal attacks undergoing some minor tweaks and many of his combos working differently than in TvC. In Japanese, Ryoutarou Okiayu reprises his role once more; in English, he is voiced by a new voice actor once more, this time being Johnny Yong Bosch.
 * In his ending, he is assisted by Silver Surfer in returning to his world, but winds up in the Neo Arcadian era instead. Silver Surfer informs him that this time and world already have a Zero, but goes by the name of "MegaMan Zero", expressing his confusion over this. In Ultimate Marvel vs. Capcom 3, the ending has an additional line of dialogue. After Zero claims he is not Mega Man Zero, he further adds that "if there ever was such a being" in his bewilderment. This is only semi-ironic since Mega Man Zero and Zero are the same person, just from different timelines. Of course, Zero wouldn't know that Mega Man Zero is his future self.
 * His fighting stance in Tatsunoko vs. Capcom and Marvel vs. Capcom 3 is a direct homage to his Mega Man X series' stances (even though they look very different from each other), with his TvC stance having Zero's both fists clenched (Mega Man X4-5 stance), and his Marvel vs. Capcom 3 stance with the leading hand open (Mega Man X6 stance). His standing light, medium and heavy attack in both games are based on his basic attack combo, his crouching medium being based off of his crouching attack, and his jumping medium being based off of his normal midair slash; all three of these however are from Mega Man X4-5 as opposed to X6 especially with the pre-X6 saber. However, all animations look different because the Z-Saber is holstered on the inside shoulder in his stance, rather than the outside shoulder like in the X series' sprites (and in canon via the artworks, also being sheathed over his left shoulder). Curiously, his Z-Saber stays the same way it does in X4-5, and can pull off skills from X6 and onward to Zero despite not having the saber from X6.
 * Zero's alternate colors all resemble other characters from his games: The blue one being based on X, the black one having more resemblance to his older brother Bass than to his actual black armor, and the purplish one resembling Axl more than his Zero series counterpart.
 * He appears in Nova's ending as part of the new Mega Nova Corps alongside Mega Man, Roll, Proto Man and Beat.
 * In Ultimate Marvel vs. Capcom 3, he gains three new colors, one for his Mega Man Zero version, another based on Vile and the last based on X's First Armor from X1. His X scheme, however, is removed in this version.
 * Additionally, one of Zero's new winquotes snidely mentions X (more specifically, his win quote against Hawkeye: "You're very cunning. You have that in common with X. You also lost to me, so you share that too."), which some see as a response to many fans' negative response of his absence in the game. Ironically, X himself is his DLC costume in Ultimate.

Project X Zone
Zero (in his X series appearance) appears alongside X as a playable character in Project X Zone. He, along with X and Vile, first appear in the game during Chapter 20, and is once more voiced by Ryoutarou Okiayu.

Early on during Chapter 29, Zero expresses shock upon noticing Iris, who appears alive and well. After hearing that she still wishes to live in a Reploid only world together with Zero, the latter reminds her that such a world is nothing more than an imagination. However, Iris then asks him if such a world is meant to be his purpose and desire, which is partly why Iris appeared. Zero then suffers an emotional breakdown, questioning himself about whether or not a Reploid only world was what exactly he was fighting for. He then gets taunted by Vile in the process for getting emotional over a girl's wish, claiming that the former is exactly the same as the latter before. Zero becomes paralyzed with anguish and is unable to move.

Confused about Iris at first, the other characters present then realize that Zero is in trouble, and that they and X must protect him from danger, while attempting to defeat Vile at the same time. The game splits the winning conditions down to two options: reach Zero by the end of the ninth turn or defeat Vile, otherwise a game over will be declared. Until then, X's unit is paralyzed and unable to fight.

After any of the other party members reach Zero and heal him, he eventually recovers from his emotional breakdown and recalls his duty as a Hunter, and tells Iris that a Reploid only world is impossible. Aura from .hack appears and states that Iris and her feelings are not supposed to be present, hence causing her to fade away. Before she vanishes however, she gently suggests to Zero that things between them are okay, and encourages him to never give up before bidding him farewell. His resolve restored, Zero confidently declares he will rejoin her someday.

He uses Rakuhouha alongside X's Nova Strike (while the latter dons the Ultimate Armor) during their special attack, and uses Genmurei alongside X's Hadouken during their multi attack. The latter is learnt right after Zero is rescued.

Other techniques that Zero uses in this game include Kuuenzan, Ryuenjin, Hyouretsuzan, Raijingeki, and Shippuuga.

Mega Man Archie Comics
The cover of Issue 35 implies that Zero will make an appearance in The X-Factor second part. Despite The X-Factor taking place months before Sigma's rebellion, Zero is depicted in his Mega Man X2 armor. Prior to his formal debut, Zero appeared in the previous issue in its Short Circuit, where like X, he was excited about appearing in a Mega Man comic until Mega Man escorts X off the premises. In Issue 35, Zero makes a brief appearance in Sigma's explanation of what the Maverick Hunters are, where he is fighting Sigma while he was still a Maverick. In Issue 37, Zero, investigating an explosion, teleported in and grabbed one of the two people responsible. He then assuaded X of coming close to becoming Maverick when the latter warned him that the two perps, although dangerous, were still human, and preempted X's thanks for saving him. Zero also explained the history and motives of the group the two people belonged to, the Emerald Spears. He later appeared in Mega Man Issue 38, where he, alongside a Maverick Hunter task force summoned by X under Dr. Cain's orders composed of himself, Vile, and three unnamed Reploids, saved X from the Wily Walker while he held it off, and then fought against the Wily Walker and telling X to locate Dr. Cain to see if he discovered any weaknesses in the Wily Walker.

Cameo appearances

 * Zero can be seen in the background of the Running Battle mode from Super Gem Fighter: Mini Mix.


 * Zero has a card in all games from the SNK vs. Capcom: Card Fighters series.


 * In Mega Man Legends and Mega Man Legends 2, an item called Zetsabre can be found, which can be used to produce the Blade Arm. Zetsabre is a mistranslation of Zero's Z-Saber.


 * A poster of Zero, in his "Black Armor", can be seen in the general store of Yosyonke City in the game Mega Man Legends 2, where he is described as some sort of comic book hero. Upon closer inspection, the image of Zero himself seems to have been taken from Mega Man X4. 


 * Zero has a cameo appearance in Higsby's shop in Mega Man Battle Network 3 White version. In the Blue version of the game it's a poster of SharkMan.


 * An actual NetNavi bearing the name Zero appears in the game Mega Man Network Transmission, and the anime Rockman EXE Stream and Beast, and is one of the few characters from the Mega Man X series to receive a NetNavi counterpart. Here, he appears somewhat identical to Zero, but with a more demonic appearance, as he does not appear to have a human face and breathes in a manner similar to Darth Vader. Like his X counterpart, Zero still has an affinity for blade weapons and also serves as a virus being. However, unlike his counterpart, this Zero is the virus, but he still follows orders without question. In the conclusions of the series, Zero begins to show compassion, and even sacrifices himself in Beast+. However, the canon ending of Transmission gives Zero a NetNavi identity as Zero.EXE, now free to roam the Internet and explore the world to make new friends, though his activity is to be monitored by Science Labs, where he now thrives. In addition, players can receive a Z-Saber chip for Mega Man Battle Network 4 by linking up with another Game Boy Advance that has Mega Man Zero 3 inserted. It can be received in Battle Network 5 by doing a certain liberation mission. Although it was an intended Program Advance in Battle Network 6, it was scrapped, but players can still hack the game to trigger it by replacing another Program Advance.
 * Zero appears in Street Fighter x All Capcom.

Arsenal
Zero is a very adept combatant on the battlefield. His power far exceeded, but now rivals that of X's. His power as a robot from a past age is considerably exceptional in the Maverick Wars. In Mega Man X, Zero was equipped with a powerful buster weapon known as the Zero Buster, but X2 and onward, Zero wields a melee energy weapon known as the Z-Saber, a weapon with a blade composed of pure destructive energy, modeled after the lightsaber of Star Wars mythos. It is for this reason that Zero is often used for seasoned players as he is required to fight up close rather than at a distance. His first playable appearance in Mega Man X3 is more or less essentially a future representation of how X will turn out, unleashing double charged shots and the almighty Z-Saber which fells bosses with a few mere swipes. Unlike his comrades, Zero does not copy the powers/weapons of defeated Mavericks, but instead, learns special attacks known as Techniques (必殺技) in the Mega Man X series and as EX Skills in the Mega Man Zero series, which are attacks based on techniques utilized by bosses. He does not require the use of a buster weapon as the attacks often utilize his hands or enhances his Z-Saber power by empowering the blade with elemental properties. The Zero Buster can be utilized from both arms, as evidenced by some gameplay and cutscene representations interchangeably showing the buster arm as being his left or right.

Unlike X, Zero cannot obtain performance-enhancing armors, with a few exceptions. This is due to the fact that during the time Zero was created, both Dr. Wily and Dr. Light could not prepare any future armor enhancing upgrades for him, thus Zero's durability stayed consistent, making him a traditional Glass Cannon. Defined in SNK vs. Capcom: SVC Chaos, Tatsunoko vs. Capcom, and Marvel vs. Capcom 3 (more so in terms of his bio), Zero is shown to not be so overly strong (unless under the Maverick/Zero Virus when he was first found or in his Awakened Boss fight in X5) as his Marvel vs Capcom 3 power grid statistics gives his Stamina rating a 3/7, but his other stats (Strength, Speed, Intelligence and Energy Projection) a 5/7, with his Fighting Ability as a 7/7. This shows that what Zero lacks in raw strength with the absence of the virus he makes up for extreme fighting ability and skills in many other fields, enabling to out-duel/wear down nearly any foe, along with showing extreme adaptation to much of his battles. This is expressed in the aforementioned fighting games where Zero has low health and average attack, though many claim him to have some (if not many) of the best combos (even loops or near/true infinites) out of all characters. In Ultimate Marvel vs. Capcom 3, Zero (like several characters from the original version to the revision), has had his power grid changed. His Stamina and Strength are now 2/7, his Intelligence a 3/7, and all the rest of his other stats are now 5/7. This shows that not only Zero puts more than just skill into his fighting ability, and that he uses all his speed and knowledge to back up his fighting prowess. His "medicore" intelligence also shows Zero tends to clear his mind during fights for better focus.

The original Mega Man X games, however, have Zero's Z-Saber be able to destroy several normal enemies in a few blows. The fighting games seem to decrease it to give more balance, and coincidentally give a possible accurate description of Zero's statistics. Zero may also be aware of his low durability (in comparison to his comrades), and may also have enough skill to last in a fight to fight/parry off any hit that comes to him, describing more of his skill as a Master Swordsman. This makes him a rather unique Glass Cannon as he not only he's weak on defense and strong on offense like the other kinds in fiction, but Zero has skills in several other fields of battle with great ability to adapt to practically any opponent he fights. (Glass Cannons usually have raw power, which Zero seems to lack often.)

Zero's long combos in fighting games seems to nod at his personality as well, taking note that he shows no mercy to his enemies as he basically never holds back on them, showing he always fights to the best of his ability. This shows that Zero is somewhat more powerful than he lets on in-universe.

By the time of the Mega Man Zero series, Zero had discarded his Zero Buster, replacing it with the Buster Shot, a regular laser pistol that he fires by hand. Originally ineffective against Pantheons, it was considerably enhanced through Zero's power supply.

Marvel vs. Capcom 3 profile

 * Real Name: Zero
 * Occupation: Maverick Hunter
 * Abilities: Has great physical ability as well as excellent skills with a variety of weapons. He is able to learn the abilities of the enemies he defeats and add them to his existing arsenal, making him even stronger than before.
 * Weapons: His primary weapons are the Z-Saber, an energy sword, and his Zero Buster, a weapon capable of firing energy shots.
 * Profile: Ever since being found in a cave by Sigma, he has worked tirelessly as a Maverick Hunter. Beneath his cool exterior lies an extreme intorelance for evil; once he gets into a fight with a Maverick, he won't stop until his enemy has been mercilessly cut down. He is best friends with X of the Maverick Hunters' 17th Elite Unit.
 * First Appearance: Mega Man X (1993)

''Note: Capcom characters in Marvel vs. Capcom 3 don't follow the standards of Marvel's Power Grid. Zero's power grid statistics also change in Ultimate Marvel vs. Capcom 3. (Strength and Stamina becomes 2/7, Intelligence becomes 3/7, and all other stats become 5/7).''

Merchandise
Zero had several interchangeable armor models released by Bandai before the line of toys was retired. Among them were:


 * Zero - A normal model of Zero with his armor from X3 and up. Features his Z-Buster and Z-Saber.
 * Plated Zero - A plated version of his normal model.
 * Transparent Zero - A clear version of his normal model.
 * Irregular Hunter Zero - Zero with his black armor. Features his Z-Buster and Z-Saber.
 * EX Armor Zero - A model exclusive armor for Zero with new shoulder pads and buster.

Because the line of models were canceled, these are very rare.

Trivia

 * According to Keiji Inafune's, as he designed Zero, he invisioned him as the new "Mega Man" and wanted him to be a playable character from the start. Keiji wanted to introduce something new and different to the franchise, but understanding that it would not be wise to completely go against everything that had already been established (also fearing that Zero's drastic appearance would receive a critical reaction), he did not mention this idea to his superior and submitted Zero as the sub character to Hayato Kaji's "Mega Man" (X) as originally intended.


 * In Mega Man X4, Zero was actually going to have his own Ultimate Armor, known as "Mega Armor", instead of his Black Zero recolor. The designer of the original X's Ultimate Armor said, "The truth is, Zero was going to have a Mega Armor, too. For various circumstances, we wound up with just X this time. You want to know what his Mega Armor would have been like? Well, it has to do with Zero’s connection to W… actually, I’m not allowed to say any more than that. But, at least I can show you the rough design. I hope that sometime it will see the light of day. That’s all for now! Enjoy Rockman X4!"


 * Although Zero and X aren't technically Reploids (robots based on X's schematics, "replicated androids"), as they are original androids from the past (technically making them "Robot Masters"), they are known as such because the term Reploid is used for all androids with human-like A.I.


 * In Mega Man X1-X4, Zero's eyes are green in-game and blue in artworks. His eyes completely changed to blue in Mega Man X5 onward. His eyes are also green in Mega Man Maverick Hunter X and Tatsunoko vs. Capcom. In the Zero series, his eyes ranges to black to purple.
 * Zero has been depicted with a full head of hair in manga form, but never in the video games. In the Rockman X manga, Zero's helmet is constantly removed, either by himself or due to the helmet being damaged in battle. He is shown to primarily keep his hair slicked back, although it appears more unkempt following larger battles. In the Rockman Zero manga, Zero's helmet is used as a signal to display his split personality syndrome; the cowardly inept personality appears without a helmet, and features loose unkempt hair, while his stoic combat-ready personality appears wearing the helmet.


 * The events during and after Mega Man Zero 4 suggest that Zero has finally died; however, to this day, this was not officially confirmed (like mentioned above, the Mega Man Zero Official Complete Works claim his fate is still unknown). This would later be repeated in Mega Man ZX Advent, where Model Z disappears under similar circumstances.


 * In Mega Man X5, if the player looks carefully at the intro sequence, where there are green words scrolling about the screen, one of the words say "Wily". This is another hint at the fact that Zero was created by Dr. Wily.


 * In the X series, Zero is a Maverick Hunter fighting against insurgence and rebellions caused by Mavericks. In the Zero series, Zero is part of the rebellion against the current government, in the process becoming labeled a Maverick himself.


 * Of all the characters to have appeared in the series, Zero is unique in that his Japanese voice actors differ in the series he appears in. In the X series, his voice actor is Ryōtarō Okiayu, while in the Zero series, his voice actor is Yuuto Kazama. The voice change is evident as the former reprises the role for Maverick Hunter X, which the Zero series predates as well as X7 and X8.


 * It's rather interesting how Zero, a creation of Dr. Wily, actually ended up fulfilling Dr. Light's dream instead of Wily's - in conclusion of a lifetime fighting against hordes of Reploids based on Light's creation, no less, whose leaders and/or master manipulators often carried even darker ambitions than Wily.
 * Also interesting is how despite not being intended to be Three Laws compliant, at the end of Mega Man Zero 4 where Zero fights Weil, Zero unwittingly follows the fittingly named "Zeroth law", which was made to prevent robots from harming a human, unless said harm would benefit humanity in general.


 * Zero is one of the few main characters that actually disappear canonically with no apparent explanation (and the most famous, being that he's done it time and time over).


 * As Model Z, Zero is the only Biometal to actually attack when not MegaMerged, paralyzing opponents while not even wasting a drop of his energy.


 * Having been completed by Dr. Wily between the classic and X series, Zero is the longest-lived robot in the Robot Continuity, with an (ultimate) age of termination of 300+: 100+ for the time between the classic and X series, 100+ more for the Maverick and Elf wars, another 100+ for the inactive hibernative state in which he begins the Zero series, and four for the whole of the Zero series, possibly longer given his unknown fate at the end of Zero 4.


 * Zero, or some signature of Zero, appears in every series in the main timeline (in the classic series in Mega Man 2: The Power Fighters, throughout the X and Zero series, in the ZX series as Model Z, and in the Legends series in the form of his Z-Saber/Zetsabre). He is the only character in the entire franchise that appears in every main series thus far. Additionally, he appears in Mega Man Network Transmission as Zero.EXE.


 * Interestingly, his bio in Marvel vs. Capcom 3 states that Sigma discovered Zero in a cave, which is incorrect as he was found in a desolate laboratory by Gamma's unit, which met an unfortunate demise upon awakening him. Sigma however only fought Zero, and barely made it out alive at a terrible cost.


 * In Ultimate Marvel vs. Capcom 3, Hawkeye refers to Zero as an, "Angry space midget with a sword." Zero's win quotes also mentions X as being cunning, but also shares that X also lost to him. With Frank West, he calls him a civilian, and his win quotes when defeating Frank West refer to his camera as a "photo capture device". Zero likely refers to it in this technical sense because cameras in the future obviously look much different than the one Frank uses.
 * In both versions of Marvel vs. Capcom 3, Zero will say, "Another souless copy." when encountering himself. This is a possible reference to both Mega Man X2 and X6.


 * The theme when Zero is discovered in Mega Man X6 is a remastering of Variable X from the first Mega Man X game.


 * In both versions of Marvel vs. Capcom 3, when Zero uses his Genmu Zero attack, if one sees Zero carefully, he will be emitting an aura similar to his Maverick state in Mega Man X5 when he executes the attack.


 * Compared to other characters, Zero probably has the most love interests:
 * Many fans believe that in Mega Man X4, Zero was in love with Iris and vice versa.
 * In Mega Man X8, Zero's Navigator, Layer, shows signs that she has a crush on him many times throughout the game.
 * Throughout the Mega Man Zero series, it's been hinted that Ciel and Zero have feelings for each other.
 * Also in the Zero series, the Neo Arcadian guardian, Fairy Leviathan, frequently flirts with him prior to their battes.
 * Despite the many love interests, it's never been officially stated that Zero had romantic feelings for them in return, although he seemed to regard Iris with the most emotion.


 * Grolla Seyfarth, a character from a Japanese doujin soft series, Rosenkreuzstilette, bears many allusions to Zero from the Mega Man Zero series.
 * This is actually somewhat ironic, as this character's nemesis, Iris Sepperin, resembles Ciel slightly in appearance, but Copy X and X series final bosses Redips and Lumine in status and personality.