Omega

Omega (オメガ), dubbed "the Devil Reploid", "the Ultimate Reploid" and "perfect ruler" by Project Elpizo, is a massive Reploid created during the four years of the Elf Wars. He is Dr. Weil's greatest creation and was made to be the perfect ruler, namely by storing and utilizing the Dark Elf in order to mass-control Reploids remotely, thus preventing them from becoming Mavericks. He plays a major role in Mega Man Zero 3 as the main antagonist (though secondary in the grand scheme) and final boss, and also appears as a secret boss in Mega Man ZX.

Appearance
In his default form, Omega is a large Reploid with a distinct knight-like theme with a long coat. His color scheme predominantly features white with black in the center of the torso and the face of the head. He has long, pale pink hair rising from the top of the helmet that reaches his feet. He has detachable arms, which feature gigantic hands with black spiked wrists and razor sharp claws.

Omega's true form is the original body of Zero. It is the same as the fake body Zero had during the Mega Man Zero series, but with a darker red color scheme. It is unknown if this is an artistic change or if Zero's original body was modified between the Mega Man X and Mega Man Zero series. It should be noted that Zero's long hair does not emerge until immediately prior to Omega fighting Zero at Weil's command, implying that Omega's hair, and by extension, Zero's hair, was retractible.

Personality
Omega is first depicted as a silent, but loyal servant of Dr. Weil. However, as the story progresses, he is revealed as an insane Reploid with a god complex. He is a bloodthirsty tool in Dr. Weil's ambitions and is absolutely obedient to his commands, very similar to what Zero was intended to be for Dr. Wily. After returning to Earth after spending a century of exile in space, he developed a grudge against Zero, because he was defeated by Zero despite the latter no longer being in possession of his original body. Also, Omega's ability to speak was reduced to minimum in his exterior armor; in fact, the only words he ever says in this form are a long, drawn out "Zero" and "Lord Weil". Other than that, he doubtlessly believes in Weil's insane purpose for him, as a "messiah" of the new world order and "God of Destruction".

In the manga, Omega is very different. He is depicted as an average Reploid hunting the Dark Elf, and dislikes Zero, though he doesn't appear to hate him, since he cooperates with him in one chapter of the manga to defeat zombie Reploids. Ironically enough, this version of Omega is also deathly afraid of zombies. Also, other than being a rival of Zero, he has absolutely no ties to Zero whatsoever, unlike in Mega Man Zero 3, where he inhabits Zero's old body. The concept of Omega having a similar body to Zero was instead given to Roze, who was an actual duplicate rather than the original body.

Rockman X DiVE expands on Omega's personality a bit, namely, it reveals that he not only believes himself to be the messiah, but also believes himself to be the true Zero and cannot seem to comprehend how the other characters seem to speak about Zero as if he were someone other than him.

The Elf Wars
After the Maverick Wars had been ended by the powers of the Mother Elf by reverting the viral infection of Reploids caused by the Sigma Virus, Dr. Weil, a weapon researcher and DNA revival specialist who had worked at the same laboratory as the unknown female ancestor of Ciel (who had researched Zero's body) in order to find a way to end the war, felt unsatisfied with the result of the solution. Thinking that it wasn't enough to simply cure the Reploids of the virus while they still posed a threat to society due to their free will, he decided to create his own, radical solution, while making himself ruler of the world in the process. Project Elpizo was the end result: to create a Reploid who would become the perfect ruler, by using the power of the Mother Elf to control all the Reploids in the world, thus preventing them becoming Mavericks in the first place.

However, since the world was at peace at the moment thanks to the Mother Elf, he needed to give the government a reason to sanction Project Elpizo. He secretly stole and took control of the Mother Elf and reprogrammed her into the Dark Elf, whose purpose was to create Maverick outbreaks by brainwashing Reploids. Baby Elves, small copies of the Dark Elf, were mass-produced to cause violent Maverick outbreaks worldwide.

As new Mavericks arose and caused terror and destruction in scales never seen before, the government heeded Dr. Weil's pleas and sanctioned Project Elpis to bring this new and devastating conflict to an end. For the project, he was given Zero's body, which possessed the necessary virus countermeasures for creating the perfect ruler, Omega, the messiah of Dr. Weil.

For Omega to control all Reploids worldwide with the Mother Elf, a massive armor was constructed around Omega for the Mother Elf to fuse with it. In addition the armor also boosted Zero's body to its absolute limits and granted it the ability to regenerate any damage (Due to the limitations of the GBA, it was unable to display Omega's mobility and agility). Along with the armor, Omega received new weapons, suitable for his new size and weight. Unknown to everyone Omega received a new personality, which was absolutely loyal to Dr. Weil's orders. With Omega completed by fusing it with the Dark Elf, the baby elves would be redundant as they were no longer needed. (Though they could be still used as attack dogs if needed.)

In the fourth (and what would be the last) year of the war, Zero, in possession of a new body Ciel's ancestor created for him, would wake up so he could fight alongside X against the new threat. At some point during the conflict, which were now known as the Elf Wars, Zero reclaimed the Dark Elf from the mavericks and used her to bring the uprisings to an end.

It was then where Weil revealed his true colors and ordered Omega and a group of Mechaniloids, similar to Neo Arcadia's later Golem models, to attack his former allies. However, because Zero reclaimed the Dark Elf in time, Omega was unable to fuse with the Dark Elf. He was defeated after a hard battle by X and Zero using the Final Strike, with Zero in particular having an epiphany about what his true intentions of his powers actually were, that they were to protect his friends and not for destruction.

In the aftermath of the war, Omega was sentenced to exile in Earth's orbit sealed within the Forbidden Ark by the Eight Gentle Judges (Who were actually created by Weil in case Project Elpizo's ideas for true peace failed), destined to spend the rest of eternity around the earth. However, things would take a different path...

Mega Man Zero 3
Two months after the Dark Elf had been released from her seal in Neo Arcadia by Elpizo, strange energy readings similar to that of the Dark Elf were detected by the Resistance in a frozen tundra. A reconnaissance unit, consisting of Zero, Ciel and a few Resistance soldiers was dispatched to analyze the anomaly. Upon arriving at the location, they found a Derelict Spacecraft. The closer they got to the ship, the stronger the readings became and Neo Arcadian troops had already cordoned off the area. When Zero arrived at the ship's entrance, he was intercepted by Sage Harpuia, who merely ordered him to retreat at once as there were things of bigger importance now than dealing with him before disappearing inside the ship. A strange, yet familiar growl reached Zero's ears from the inside, seemingly calling for him. Zero fought his way through the hostile forces and entered the core of the ship, where fighting was already in progress. At the core, he saw Fighting Fefnir, Fairy Leviathan, and some Pantheon Hunters battling an enormous Reploid, Omega, but were unable to do so much as damage him, while the Hunters were destroyed during the Messiah's entrance. Weakened and damaged, the two Guardians teleported away, leaving Zero and Omega, whom Zero recognized as the one that called him, all by themselves.

The two battled for awhile, with Zero seemingly immobilizing the giant Reploid, but unable to severally damage it due to its ability to regenerate himself. Even after Harpuia joined the battle as well, he managed to hold his ground. At that moment, Dr. Weil showed up at the scene, halting Omega from continuing battle, as Harpuia was now his comrade as a Neo Arcadian. Upon introducing himself, Copy X appeared as well, having been revived by Weil. Even though Harpuia warned him about all the havoc that Omega and Weil caused in the past, they were pardoned by Copy X and given the permission to enter Neo Arcadia in order to serve Copy X and to regain control over the Dark Elf. All of them (save for Zero) then left to Neo Arcadia. It was later found out that since Omega had returned from outer space, strange green portals had appeared in different locations which seemingly made it possible to travel between the real world and its Cyberspace shadow world.

Back at Neo Arcadia, Harpuia desperately tries to talk Copy X out of trusting Weil, though Copy X claimed his banishment was not a legal one and that, even though his actions caused the most devastating war in history, his banishment was not the verdict of a fair trial. When the Dark Elf was located in Area Z-3079, a residential district with the utmost distance from the Neo Arcadian center, Copy X stripped the remaining three Guardians of their powers and duties and handed all their military command to Weil in order to catch the Dark Elf.

Omega was transported to the missile base near the Aegis Volcano and loaded into a missile which was then fired into the direction of Neo Arcadia to catch the fugitive Cyber Elf. The Resistance, which intercepted transmissions about the start of the missile, sent Zero into the area to halt the take off of the missile. Though he didn't make it in time to stop the take off, Zero boarded the missile to stop Omega, who was at that time immobilized within.

However, he was intercepted by Crea and Prea, two Baby Elves which managed hold Zero off Omega long enough for the missile to reach its destination. The missile crashed into the district, killing many innocent people and totally devastating the area. When Zero regained consciousness, the Dark Elf was in front of them, as well as Omega. The giant Reploid had caught her and absorbed her into his body, causing his white and red armor color scheme to turn gold and blue and boosting his abilities to new heights, thus the perfect ruler was finally created. Harpuia, who couldn't watch anymore, turned against Copy X and tried to fight Omega; however he was no match for him. It was only due to the lucky timing of the Resistance's Operators that Zero and Harpuia managed to survive their encounter with the Devil Reploid.

After Zero managed to stop multiple Neo Arcadian attacks aimed at the Resistance base, he went to stop the problem of the cause, Copy X. The two of them fought with Zero emerging victorious. Copy X called for Weil's and Omega's assistance, however both of them had already disappeared to another location after stealing everything they needed from Neo Arcadia's supplies. When an enraged Copy X tried to transform into his seraph form to destroy Zero once and for all, a self-destruct program within him was triggered, installed into his body by Weil himself, killing him. Shortly afterwards, Weil claimed leadership of Neo Arcadia by, as well as encouraging the citizens of Neo Arcadia to support his cause to terminate the extremists.

Zero was then sent to find out more information about both Omega and his creator. Eventually, he located a sunken data library with information about both of them, as well as their actions during the Elf Wars, despite having to deal with Volteel Biblio. Soon after this, Weil had finished the final modifications on Omega to grant him the power to control every Reploid on the planet. While X defended the inhabitants of the Resistance Base with his powers, Zero (who was unaffected by the Dark Elf's/Omega's powers, because his copy body possessed the same imperfect virus counter measures of his old body) rushed for Weil's lab.

He managed to defeat Weil's servants, the Eight Gentle Judges as well as Omega in his empowered form. Enraged by his defeat, the giant Reploid released the powers of the Dark Elf within him, transforming him into a larger and mightier form of himself. It resembled a strange fusion of himself, X and Zero, armed with a giant saber and a chargeable buster cannon. However, Zero again defeated him. Omega's remains and Zero fell down through the floor of Weil's laboratory, only to find themselves right at the place where Zero was found by Ciel. When they did, Weil revealed Omega's secret to him: That he [Zero] was nothing more than a clone, while the real Zero is in fact Omega. From the remains of Omega's battle body, Omega's true form emerged, a Reploid looking exactly like Zero, however with Zero's original color scheme and using multiple attack patterns and moves Zero had previously used in the Maverick Wars and now forgotten (for the most part), along with massive upgrades. Yet, after a fierce battle, Omega was defeated.

Yet, the battle wasn't completely over as Omega used the Dark Elf within him to heal his wounds. The remaining three of the Four Guardians appeared to assist Zero in defeating Omega. X also appears, telling Zero that Weil was only telling half the truth: Omega may be possessing his original body, but the "clone" is still the real Zero, by virtue of having Zero's heart and soul. Zero regained his strength to deliver the final blow, destroying Omega for good, resulting in a massive explosion that only Zero himself survived due to the protection of the now cured Mother Elf. The destruction of Omega also caused the dimensional portals to disappear. In the end, Zero was still Zero, whether spending his life in a copy of his original body or not, his heart was still the right one.

Mega Man Zero 4
Although Omega does not appear in the game proper, owing to his destruction at the end of the previous game, he appears during and is alluded to during the beginning narrative. In addition, he makes a brief cameo appearance when Neige explains to the Resistance that Dr. Weil has made life in Neo Arcadia so unbearable that not even humans were willing to stay in the former human utopia, where the still for Weil was taken during Weil's speech to the Resistance upon using the powered up Omega to control all Reploids across the planet.

Mega Man ZX


Omega appears as an optional boss character in Area N of the game. Due to the massive explosion after his final battle with Zero, a rift between reality and Cyberspace was caused, similar to what happened when Omega returned to Earth after his exile. The Omega appearing in Area N is not a rebuilt version of the Reploid but actually a corrupted memory file that remained of Omega when he was destroyed. This is believed to be the case because of the environment around him constantly changing between the normal background of Area N and that of the final battle of Zero and Omega.

Omega operates identically to his final form in Mega Man Zero 3, with some lethal differences. Attacks don't stun him as frequently, and he is significantly faster and more aggressive. Here, he uses his Ranbu combo much more often. In addition, his Rekkoha now restores 8 units of his health. His delay time frames to perform another move has been reduced to zero frames, causing Omega to be constantly attacking the player, making the battle much more hectic than in Zero 3. Unlike the other bosses found at Area N, Omega is the only one that will not respawn the minute the player enters the room after defeating him. For one to fight him again, the player has to leave the area first and then return for a rematch.

After he is destroyed in Normal or Hard difficulty, he will leave an item called "Mysterious Stone". After clearing the game once, the stone can be taken to resident scientist of the Guardians Fleuve, who'll analyze the stone and transform it into the Biometal Model O which lets Vent/Aile become Omega, including all powers and attacks he possessed.

It is unknown if Omega's Biometal form in Mega Man ZX is part of the canon story or simply a gameplay extra. The latter one is what is commonly believed, but there is vague evidence by Flammole during his first battle, he said that Serpent send him to search a Biometal in the grounds, which implies its existence, and as he sensed something entirely different from Model W.

Forms and Abilities
Omega has many powerful abilities, which is why he is feared by all, Reploid and human alike. These are unique to each form, total of three forms to begin with.

First form
Omega's first form is his original body, the "Devil Reploid". He is at his most recognizable in this stage. His claw-like hands can detach as Fefnir found out to his cost. He's also extremely durable; Fefnir and Leviathan could not hurt him. However, both Zero and Harpuia were capable of inflicting some damage, with the latter in particular being severe enough that only Weil's interference spared him.

This stage later evolved into a golden state after absorbing the Dark Elf, boosting his power yet again and granting him the ability to take control of all Reploids on the planet at once. The main difference between the original and golden states is the amount of damage that Omega delivers, the speed of his attacks, and the last saber attack. His durability in this form was also significantly increased, as evidenced by how he completely shrugged off Harpuia's attacks in his golden form whereas earlier he was significantly damaged by him.

It should be noted that Omega was originally intended to be much more powerful in either form. Due to game mechanics he's just a seemingly motionless, floating enemy that could only move his hands and sword.


 * Hoop Shot - Omega's arms will detach from his body and strafe the room, firing large energy shots resembling lines of rings. The right arm hovers over the battlefield and fires downward, and the left arm moves up and down on the right side of the screen, firing lasers that dodged by jumping over them or dashing under them (depending on their height). The claws and lasers move faster in his second encounter.
 * Omega Laser - Omega will spawn three lasers in front of his torso. The lasers will hit three certain spots (near him, between him, and at the back of the room) and reflect off them. Trajectory is faster in the second encounter.
 * Piercing Sword - Omega will draw his saber and hover it over the battlefield, trying to line it up with Zero. Periodically, he will slam his saber into the ground - the third and final strike will send debris everywhere.

Second form
Omega takes this form using the full power of the Dark Elf. With three heads (Dark Elf's, X's, and Zero's, thus the "Fusion Omega" nickname), a sword so massive the tip can't be seen, and a colossal cannon, Omega is a far more formidable opponent. The monster's only weak point is the central face, a relatively tiny target. Despite these new abilities, this form still pales in comparison to the final form. Again, this form's movement and attack patterns were limited due to game mechanics and the size of the Game Boy Advance screen.


 * Spark Chaser - Omega will summon a laser that follows the player's horizontal path and only turns 90 degrees.
 * Triple Laser - Omega will fire lasers from his eyes (X head fires farthest, Dark Elf head middle, Zero head shortest).
 * Exceed Buster - Omega will fire three huge energy shots in a row. Can be dodged more easily with a charged Recoil Rod or a double jump.
 * Exceed Buster Neo - Omega will fire a laser beam; dash to dodge.
 * Binding Ball - Omega will summon a red sphere, following you and trapping Zero. If Zero is caught, it will drag Zero back to him, dissipating when it touches Omega.

Third form
Resting inside the central head of Omega's previous form is Zero's original body (with Omega's mind), upgraded by Weil to draw out its full power; Omega's normal form is just an external armor for it. Omega starts off the battle shouting out his famous phrase before his hair sprouts out and a white aura surrounds his body. Omega wields a buster hand gun (O-Buster) and a magenta-colored saber (O-Saber), both of which appear more powerful than Zero's versions, however they all cause less damage (For example: Omega's charged Saber Attack causes 5 Points of damage, while Zero's version does 8 points of damage)

He can use most of Zero's attacks from the X series. Despite powerful ranged skills, Omega truly shines in melee combat. This form can hit within Zero's invincibility frames, making attacks on Omega while flashing even riskier. All of these techniques make this form the most dangerous. Despite being much smaller, this form has the same amount of health as his larger forms. As evaluated above, he is also arguably just as strong, if not stronger. On a semi-related note, Omega's hair appears only at the immediate start of the battle, implying that Omega, and by extension Zero, is capable of retracting his hair. A similar occurrence exists with the ZX model during the Model W crisis.


 * Triple Slash (トリプルスラッシュ) - the regular attack, a 3-hit O-saber combo.
 * Charge Saber (チャージセイバー) - Omega slams the ground with the O-Saber, causing rubble to fall from above.
 * Arc Blade (アークブレード) - Omega spins in the air with the O-Saber, sending crescent waves in seven directions.
 * Double Charge Wave (ダブルチャージウェーブ) - Omega fires two charged shots with his buster, followed by a crescent wave with the O-Saber.
 * Ryuenjin (龍炎刃) - Omega does a rising slash with the O-Saber. This is a attack that Zero learned during the Great Repliforce War.
 * Messenkou (滅閃光) - Omega pounds the ground, unleashing a spread shot in five directions. This is a attack that Zero learned during the Eurasia Incident.
 * Rekkoha (裂光覇) - Omega pounds the ground, raining vertical beam pillars down to surround him, rendering him briefly invulnerable (In Mega Man ZX this heals Omega by 8 units). This is a attack that Zero learned during the Nightmare Phenomenon.
 * EX Skill: Ranbu (乱舞, "Wild Dance") - Omega lunges at the opponent and executes a deadly 7-hit combo with his saber. If Zero successfully dashes underneath him just as Omega leaps, Omega will just turn around and still try to connect the attack.

In-battle quotes

 * "Dorya" is a kiai, a shout that a Japanese combatant yells when he is in the process of performing an attack. As such, it can essentially be translated as "Take that!", as the combatant is signaling to his opponent that he will attack. It is common for "Dorya!" to be translated as "Take that!" in anime shows, including Vinland Saga.

Musical themes
His primary theme, "Exiled One - Omega -", is a dark, repetitive theme that features chants in the background. The pitch of the chants and quality vary between the soundtrack and the GBA version. In the former, they are a deep pitch, while in the GBA version, they're higher pitched, though still ominous in nature. His boss theme, "Omega Battle", starts off with a drawn out chord before having a faster-paced version of Exiled One as the main theme, which either has electronic boops (GBA) or electrical guitars (soundtrack).

His Fusion Omega form's boss theme is "Judgment Day", features tense drum beats and percussions with strings, done together to form a tense military march, before dipping down to a low pitch rumbling and then rising back in pitch to a march before looping.

Omega's Zero form boss theme is Cannonball, which is a tense, chaotic theme with electric guitar. Its remix in ZX, Cannonball - Hard Revenge -, starts off with a tense melody before picking up to a more higher pitched version of the main theme from MMZ3. The theme that's used when Omega's true form is unveiled as well as X's recollections of Omega's first defeat by him and Zero, Apocalypse Now, features pipe organs playing in a tense and ominous manner as well as slight vocalizations, as well as violins nearing the end.

Rockman Zero manga
In Rockman Zero, Omega is a normal-sized Reploid that works for Dr. Weil. He has the task to find the Dark Elf, but during his search, he fights against the new Zero in a village and is defeated. Omega attempts to defeat Zero several times, with no success. Because of his failures, Weil gives Omega the Giant Omega-DX to help him defeat Zero, but warns him that if he is not done with it in three days, he will be fired. As Omega's giant robot is destroyed, he is fired and now wanders around the village. Later, Zero saves him from Noble Mandrago, but Omega is not happy to see Zero, as he is the responsible for his current situation. He is last seen trying to defeat a "Dark Elf possessed" Zero (Zero being actually "drunken" because of cola), but Zero defeats Omega by running over him with Neige's car.

Despite their rivalry, Omega and Zero teamed up once to survive against several "zombie" Reploids. Omega has great fear of zombies, even panicking when he sees Weil's face and confuses him with a zombie. Zero also helped Omega build the Giant Omega-DX, not knowing its purpose was to destroy him, but as Zero didn't do his work properly, ignoring several parts, it resulted in the robot's destruction and Omega being fired.

Rockman X DiVE
Omega appears as a boss in his Zero form in the game, as part of a collaboration event with the Mega Man ZX series. He is also demonstrated to have the ability to levitate.

Trivia

 * Omega (uppercase Ω) is the 24th and last letter of the Greek alphabet. Ω is used as the Boss logo throughout the Zero series, but is replaced by W/V (Weil/Vile's symbol) in Mega Man Zero 4. In addition, Omega's "Biometal" in Mega Man ZX is shaped to resemble Ω.
 * A very possible reason for his naming is that "Z" (Zero) is the last letter of the Latin alphabet, and as said before, "Ω" is the last letter of the Greek alphabet.
 * Additionally, the Greek letter alpha (α) is often sequenced as 0 in the alphabet. This creates even more parallels between Zero and Omega, since they are the first and last letters of the Greek alphabet, respectively.
 * Furthermore, the term "alpha and omega" refers to the beginning and end of a subject - this can be related to how X is considered the progenitor/ alpha (beginning) of the age of reploids, and Zero's supposed purpose to surpass any robot masters ergo becoming a living iteration of the omega/end of the evolutionary cycle within the Mega Man lore. It can however also be interpreted as the reploid legacy that started with X's creation finding closure via Zero's existence to truly create peace between reploids and humankind. This ties in to the aesthetic that is evident in Omega's 2nd form.
 * Coincidentally, the Sonic the Hedgehog series also has a character by this name, his full designation being E-123 Omega. Both characters also ended up being created by a scientist voiced by Chikao Otsuka (E-123 Omega by Dr. Eggman, and Omega by Dr. Weil), the only difference being that E-123 Omega hated his creator, while Omega was fanatically loyal to his creator.
 * During the ending sequences of Zero 3, Omega Zero actually speaks with a text/dialogue box, although he only has one line. His portrait is seen as similar to Zero's, the only differences present are that Omega's eyes are red and his armor has a deeper hue of red.
 * Before Zero and Omega Zero do battle, the latter shouts a Japanese line, "Ware wa meshia nari!", which translates to "I am the Messiah!". Omega Zero uses the same line before the player finds and fight him in ZX. This fortifies the fact that many of the characters in the Zero series referred to Omega as "The God of Destruction".
 * This can be assumed as what Zero himself is intended to be in the first place, had the Maverick Virus not removed his destructive programming.
 * Omega was originally designed to be like a sarcophagus, with his true form sealed within it. The sarcophagus was designed like a giant Mechaniloid with several Ω shaped parts and a Cyber-elf shape at the head. When the final form appears, the sarcophagus splits down the middle, and the true Omega awakens from his slumber.
 * Considering that Omega is in fact an external upgrade to Zero's original body, it could be considered that technically, Omega is Zero's desired ultimate armor comparable to that of X's.
 * Omega's armor, after fighting him for the first time, emits a glow from the black parts that make up his visor, face, chest, and abdominal region upon defeat, which then seem to heal the armor, and bring the claws upward from the ground back to a levitating position where real arms would be. This could mean that his armor was made with regenerative capabilities. This makes sense in that if the armor were broken, it would have released Omega in his most powerful state (when he was in control of Zero's original body). The regeneration might be to keep the armor active and the armor itself seals and limits Omega's power extensively.
 * On a related note, the concept art for Omega showed Omega Zero in his X-series colors in a cutaway for Omega, maybe implying that Omega's similar colors to Zero in the final battle against him were due to the Dark Elf inhabiting him at that time.
 * With the change in his appearance, Omega Zero's attacks also differed from the original incarnations seen in the X series:
 * The Z-Saber combo is slightly altered between the X and Zero series, and Omega Zero uses the latter variation.
 * The Buster combo is slowed down, and, with good timing, Zero can easily dodge each shot with a jump. And the crescent shot doesn't home in on Zero, not like the incarnation seen in X5 and X6 (the latter when used by the Zero Nightmare).
 * Omega has the most amount of health in the Mega Man platform games, and it is only second to Albert (Model W) in Mega Man ZX Advent: Albert has 486 units of health (this is not official info, it was calculated while fighting the boss and shooting Buster Shot shots one-by-one) for his first form and 2 life bars (64 units, 32 each - like normal bosses' life bars) for his second one. While Omega only has nine health bars in total (three for each form). If one counts Omega's ghost from Mega Man ZX as a form of Omega, he also has a total of twelve health bars.
 * Omega is the only final boss in the Mega Man Zero series with 3 phases, while Copy X, Elpizo and Dr. Weil have 2 phases each.
 * It's interesting to mention the fact that using some cheating features, as the "Invincibility" (Not "unlimited HP" or "max HP") in both Mega Man Zero 3 and Mega Man ZX, the cheat will be ignored in Omega Zero's Ranbu and Triple Slash combo, causing unexpected damage to the player. Making Omega Zero one of the rare cases in the franchise to ignore cheating features.
 * In the background of the stasis chamber during the final battle with Omega, a piece of the rubble is identical to the iconic W of Dr. Wily and on the left, an L is resting on a giant head similar to that of X's head.
 * In the Zero Collection, the player must now attack the regenerative part of Omega to cause damage to him instead of simply attacking from the ground. Omega's invincibility timer is increased slightly, so the player can only do two attacks before the timer takes effect.
 * It could be noted that Omega is rather a "consciousness" and not a Reploid altogether, as Omega is only using Zero's original body. On top of that, Omega, despite using Zero's original body, possibly does not possess the original Z-Saber, which is in Zero's possession.
 * Omega Zero's Ranbu is a nod to a Street Fighter attack named the Shun Goku Satsu, a move perfected by Akuma.
 * Though coincidentally, Omega's voice actor voices a different character from Street Fighter as of Street Fighter IV instead (Vega AKA Balrog in Japan).
 * Omega is only one of two characters in the series to appear as both the first boss and final boss. The other example is Sigma Head.
 * Omega ties with Sigma as the largest Reploid of the series. "Fusion Omega" as large as Final Sigma W from Mega Man X5, with both forms so massive that only their faces and part of their torso is revealed on screen.
 * In Mega Man ZX Advent, there is a stretched "O" that would usually go under the player's life and Biometal gauges. This is probably a leftover from the last game, as both games were made in the same engine.
 * While Omega Ranbu did instantly kill player in one successful combo in Mega Man ZX's Hard mode, the actual damage of Omega Ranbu in Hard mode is 28.
 * Omega Zero's characterization in Rockman X DiVE has notable similarities to that of Copy X, in particular his believing himself to be perfect and unbeatable.