Zero

Zero (ゼロ) is one of the three main characters of the Mega Man X series, as well as the protagonist of the Mega Man Zero series. He also makes an appearance as Biometal Model Z in the Mega Man ZX series. 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.

Personality
As stated, Zero acts cold and emotionless towards others, even to his partners X and Axl. However, it shown that he has the capacity to care for others and to some extent, in Iris' and Ciel's case, love. Zero generally keeps his cool under most circumstances, and no matter what his enemies ever do to him, he always seems to have to be able to come up with a retort to it.

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 game, as well as during the second, where he personally promised to Harpuia that no more Resistance soldiers will come to harm as long as he's around.

Even though Zero does not openly show it, he, too, seems to long for peace between humans and Reploids. However, as stated in his previous words, Zero still doesn't have any major problems with fighting, unlike his more pacifistic friend, X; whether his enemy is a Maverick or a human (during Mega Man Zero 3, Zero commented that Dr. Weil was no different from a Maverick to him), he will fight at his best. Another notable trait is that, despite his great power, Zero has shown to be humble: he has, at times, actually viewed X as the superior Maverick Hunter, and actually considers him a hero, which seems impressive since Zero doesn't consider himself a hero. A prime example of this show of respect was in Zero's ending in Mega Man X6: the scientist who was performing Zero's sealing process asked what would happen if the world faces another crisis; Zero firmly states that the world is in good hands (X's), even when he's gone.

Origin
Zero was created by the late Dr. Albert Wily sometime in the early-21st century. His first chronological appearance was in the form of schematic blueprints during Bass's ending for Mega Man 2: The Power Fighters and described by Wily as his "greatest masterpiece." Learning from his past mistakes, including the accidental creation of Bassnium, and his construction of Bass and King, Wily constructed 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. Wily took the time to complete Zero, originally planning to use him against both Mega Man, and his insolent rebellious Bass. However, this never happened, and he was never utilized during the Wily Wars. Zero was routinely activated in a semi-conscious state during his construction, and Wily conversed with him, mirroring what Light himself did with X. Zero was aggressive and disobedient, and because of this Wily decided to seal him in a capsule. Decades later, in the early 22nd century, he was awakened by a group of Reploids prior to the first Mega Man X game.

When he was first activated, he awoke as a Maverick (by the definition of wanting to cause harm to all humans) and 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, however at the cost of a total loss of said unit. Not wanting to get anymore 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 and a 'W' symbol appeared, apparently causing Zero great pain. Sigma punched this crystal, shattering it and defeating Zero (subsequently passing on the Maverick Virus to himself). He was then brought to Dr. Cain, who analyzed him. After that, Zero recovered from his battle with Sigma and was placed under Sigma's watch. Zero did not show any 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 a somewhat mentor to X.

Soon afterwords, 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 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 pressure X into surrendering. To get Zero out of his way, he was struck by Sigma's beam saber and later abandoned while Sigma 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 4th 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. 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 a bait for X). When X was also defeated by Vile, Zero managed to break free and destroyed Vile's armor by firing a charge shot from point-blank range, which was a successful, yet fatal action. Afterwords, 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.

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 Zero's unique body structure.

Six months later, a group of three Mavericks, calling themselves the "X-Hunters" (Counter Hunters in Japanese), contacted the Maverick Hunters and claimed to be in possession of all parts of Zero. The X-Hunters challenged X to a battle in order to win Zero's remains. (The Japanese version of the game however claims that they actually rebuilt the parts and did not use remains from the previous game.) It was Serges (Sagesse in Japanese) who constructed the parts and upgraded the body with the specs Zero was originally intended to have, including reinforced shoulder plates and Z-Saber.

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 doppelganger 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 very end of the Japanese version of the game, Sigma mentions that Zero is the last of "Wi...numbers", implying that Zero is the last of the "Wily numbers", or advanced robots built by Dr. Wily.

As a non-canon scenario in X2, in case 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 assisted 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 digitalized 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 digitalized 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 digitalized 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 was destroyed by him, however the Mechaniloid managed to hit Zero in a last resort attack. The crash of the Mosquito 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 Mega Man 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 fully controllable character with his own story also marked his most tragic point in 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 of 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 for a moment and as a request for interrogation was declined, the Great Repliforce War broke out.

When the Repliforce was labelled 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, who was by now Zero's girlfriend, assisted Zero on his missions as being his operator, like during the Erasure incident. 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 love 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 side however stated that someone had to stop Repliforce at all costs, much to the grief of Iris. 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 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 programing, 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 together with him, 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 (he yells "NO, THIS ISN'T HAPPENING! THERE'S NO REASON FOR ME TO GO ON!! WHA.. WHAT AM I FIGHTING FOR!!!" at the end). 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 over the 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. 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 answer to X 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 the 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" (Enigma is German for mystery, an odd name for a gun) 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, a 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 be directed right into the colony to have have it self-destruct right at the Eurasia's 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 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 Zero Virus 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 not showing any Maverick behavior. Not wanting Zero to become a Maverick, X would fight his friend in order to have him being brought back to Hunter Base. Eventually, the battle would end in a draw (apparantly, both used "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, majorly damaging him. The remains of Sigma attacked Zero and X one final time, impaling both of them in 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, 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. Dr. Light, who repaired X at the end of X5, denied knowing who repaired Zero. Some believe it is Gate's ally, Isoc, as he is the only Reploid who claimed to have seen Zero before X found him, and he demonstrates an odd obsession with Zero, even laughing joyously when Zero defeats Gate's own men, but in this very cutscene Isoc says, "Now that I know you are alive I can capture you at anytime." If it was Isoc, he would have known Zero was alive. Again, in this game Zero has his Z-Buster with slight differences: It takes a bit less time to use than in X5 and it seems to do more damage at a close range. 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 Sourcebook "Rockman Zero Official Complete Works" 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 2 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. 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 game Mega Man X (presumably it happened when Sigma shattered Zero's head gem as X4 depicted, though the unlockable animation "Day of Sigma" in the PSP remake of Mega Man X has put a few doubts on this). This information was long-since stated in Japanese sourcebooks, 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 is joined by 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 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).

The Elf Wars
At some unknown point after his mission on Gigantis, 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 Miss 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 horrible 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
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 apparantly 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 one 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 (which was revealed to be Harpuia), 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 monstous 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 Harupia as an ally. Copy X MK II then appears and announces that he revoked Dr. Weil's exile.

After a few missions, Zero and the resistance then learn that Neo Arcadia is planning to launch Omega into Area O-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 it's 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 their destroying a human settlement just to get the Dark Elf. An invasion with three units coming from the Desert, the Forest, and Antartica then try and attack the Resistance Base. Zero manages to take down the invasion, as well as destroying a newly resurrected Hanumachine, Necromancess V, and Blizzard Stagoff. 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. Afterwards, 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 become a Seraph, despite X's warnings about a device implanted into him, but 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 enacts Ordinance 8 to become ruler.

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 in 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 forms. 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 deal more damage to 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 the peace between Reploids and humans, a promise Zero keeps to heart up to the 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.

Once all eight Warriors were defeated, Craft goes rogue and initiates a revolt against Weil on the space station "Ragnarok", aiming the station's powerful laser cannon to fire at Neo Arcadia. While the entire Resistance mobilize to evacuate the citizens of the city, Zero storms Ragnarok. Before he could reach him, however, Craft opens fire, destroying the city. Zero defeats and mortally wounds Craft. In his last breaths, Craft asks why Zero continues to fight for the humans that feared them. Zero says that he has a promise he has to keep for a friend, and that he believes in the humans that his friend trusts. Craft, repentant, asks Zero to continue living up to that promise, before shutting down for good.

All is not well, however. Even though Dr. Weil was the target of Craft's attack, he actually survives, teleporting into Ragnarok and setting it to crash into Area Zero. Zero, after going through the defenses of Ragnarok, confronts Weil, and fights him in two battles. After the first battle, the space station is damaged and begins to fall to Earth. Ciel tells Zero that he can either return to Earth at that moment, or become stranded on the station due to increasing transporter interference. He passes the offer to come back and proceeds to finish Weil off in their second battle, ultimately sacrificing himself as the death of Weil's last form causes the station to explode (though the Mega Man Zero official complete works, which is canon, mentions that his fate is unknown). Zero's (final?) action opens the eyes of many, and brings peace between the Reploids and humans left on Earth.

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 contain his memory or "soul"). Omega Zero also appears as an optional boss in Area N-1. Defeating him in Normal or Hard will allow access to a rock which gives you Model OX. Although Biometal Z is not usable by itself it can be combined with Biometal 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 4 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 death, he continues to live, resurrected in some way or another, always fighting with whoever he is with.

An interesting point in this point 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.

Other appearances

 * Zero (in Mega Man Zero form) appears as a hidden playable character in the fighting games SNK vs. Capcom: SVC Chaos and Onimusha Blade Warriors.
 * In SNK vs. Capcom, Zero is a mid-boss. 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. 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.
 * Zero (in Mega Man X 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, 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.
 * 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. (Image)
 * Zero has a cameo appearance in Higsby's shop in MegaMan 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 MegaMan 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 MegaMan 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 an intended Program Advance in 6, it was scrapped, but players can still hack the game to trigger it by replacing another Program Advance.

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.

Arsenal

 * Main Article: Zero's weaponry

Zero is a very adept combatant on the battlefield. His power 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 Z-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 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 Command Arts (more commonly known as EX-Skills) 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.

Unlike his comrades, Zero cannot obtain performance-enhancing armors, with the exception of the Zero Armor.

Trivia

 * Although Zero and X aren't technically Reploids (robots based on X's schematics, "replicated androids") as they are original androids (technically making them Robot Masters) from the past, they are known as such because the term Reploid is used for all androids with human-like A.I.
 * Zero's eyes are green in the first four Mega Man X games and Maverick Hunter X, and his eyes are blue from Mega Man X5 and onward.
 * 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.
 * Zero was originally intended to be the main protagonist of Mega Man X, according to Keiji Inafune, Mega Man's creator. However, Zero was turned into a secondary character because Capcom feared Zero's look would not be approved by fans as a true Mega Man, and convinced Inafune to use the character design widely known today as Mega Man X. However, Zero would eventually gain his own game series on the Game Boy Advance, Mega Man Zero, making him the first character in the franchise who isn't a Mega Man incarnation to gain his own official series.
 * 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 on the series he appears in. In the X series, his voice actor is Ryotaro 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.
 * 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.
 * Grolla Seyfarth, a character from a Japanese doujin soft series, Rosenkreuzstilette, bears many allusions to Zero from Mega Man Zero series.

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 was canceled, these models are very rare.

Zero from the ending of Mega Man Zero 4
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Notes and references
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