"No one can match my power. Hahaha!"
―Sigma's victory, Marvel vs. Capcom: Infinite

Sigma (シグマ Shiguma), formerly referred to as "Commander Sigma", is the primary antagonist of the Mega Man X series. He serves as the final boss in all mainline games in the series except Mega Man X8 where he is the penultimate boss in Normal and Hard mode. Once the noble leader of the Maverick Hunters, Sigma fell into insanity and turned Maverick himself, becoming the leader of all haywire Reploids and waging war on humanity. Although he has been destroyed countless times, Sigma's programming always survives and builds himself a new form, ready to menace the world once again.[1]


Although Sigma has taken many diverse forms throughout the series, his designs retain several consistent traits. His face is arguably more anthropomorphic than even X or Zero, possessing a bald human head with a cleft chin. His eyes are bright blue or white, possessing no irises or pupils, and with a scar torn over each eye (often the scars are merely aesthetic, such as in Mega Man X8 where they are straight lines running down his entire face). His tall and bulky frame resembles a muscular human body, and his color scheme always includes green and/or purple.


Sigma was originally the honorable and selfless leader of the Maverick Hunters, but after his corruption, he became a power-hungry tyrant. Amidst his madness, Sigma was a calculating and intelligent individual, and on more than one occasion, turned allies of X and Zero against them, and instigated many of the most destructive events of the Maverick Wars, including the Earth Crisis. He was proud and typically looked down on others, not hesitating to kill the weak and laughing maniacally at their expense. His previous "protection through aggression" philosophy has mutated into a huge Darwinism complex, believing that anything that is too weak to progress should be annihilated, a la natural selection.

Sigma exhibited traits of savior complex, genuinely believing that he was doing what was in the best interests of the Reploids and that the ends would justify his violent means. He was misanthropic towards the humans, believing that they had run their course and were now mere setbacks for the progress of Reploids. Despite his brutal disposition after going Maverick though, he still had some reservations, as he noticeably was disgusted with Berkana and the lengths she was willing to go to satisfy her megalomania, to the extent that he even went as far as to thank X for stopping her.

Over the course of the Maverick Wars, Sigma came to respect the rookie Maverick Hunter, X, even congratulating him during their first climactic encounter. He claimed that X's devotion to justice is part of what made him begin seeking to change the world in the first place, and he was utterly fascinated by X's powers and his inability to go Maverick. He also held an obsession with Zero, due to him being the original holder of the Maverick Virus and formerly a close ally in the Maverick Hunters. Axl, on the other hand, he saw as little more than a tool in his schemes and an outdated prototype for the superior new generation Reploids.

As Sigma is continually destroyed and resurrected, his sanity begins to degrade. The proud, charismatic warrior he is in the first Mega Man X degrades into a cackling, remorseless psychopath by Mega Man X4, and in Mega Man X6 he is borderline senile. He manages to recover a semblance of his sanity after this defeat, but by Mega Man X8 he is again a violent brute who is completely obsessed with his vision of the future.

In the remake Maverick Hunter X, Sigma is shown to have a more philosophical and level-headed personality. While he retains his distaste for humans and his desire to rule, his fascination with X's potential is much more emphasized than before, hinging his entire rebellion on the fact that X represents the future of Reploids. It is implied that he is incapable of experiencing true empathy, unlike X,[2] which is part of why he is obsessed with him. His descent into villainy is explored somewhat in the included OVA, The Day of Σ, which shows more of his stoic leadership as a Hunter and his calculating manipulation as a Maverick. He also acts as something of a mentor to Vile during Vile Mode, encouraging him to fight X in order to hasten his growth.


As the former commander of the Maverick Hunters, Sigma is a capable military leader, described as possessing overwhelming combat power and strategic intelligence. His circuitry is the most advanced of its time, which once allowed him to maintain a semblance of sanity even while hosting the Maverick Virus. When he finally gave in and turned Maverick, Sigma remained a charismatic leader with devoted servants who would go to great lengths for his sake. If his wiles are not enough to sway one's mind, he is also able to infect them with the Sigma Virus to force them into madness and loyalty. Due to his affinity with said virus, Sigma's "spirit" can also survive seemingly any physical damage that would be lethal for other Reploids. This effectively bestows him with immortality, as long as his virus has a place to go. Its intangibility also allows it to ignore physical assaults and energy attacks, except for those tuned with a Virus Buster to target the Sigma Virus's unique matrix. No solution for the virus remained ultimately effective during 21XX-22XX, as Sigma demonstrated the ability to adapt to any countermeasure. However, his viral form did remain somewhat susceptible to neutralizers and vaccines, such as the ones made by Dr. Doppler or the Mother Elf.

When not in his viral form, Sigma always has the most physically-advanced and variable Reploid bodies available at the time. His personal energy has been stated to be too powerful to even get an accurate reading.[Citation needed] He possesses incredible strength and speed, often able to move faster than the Maverick Hunters can follow, and is usually capable of teleportation. In his first body, during a conflict with the Maverick Zero, he was able to effortlessly break through Zero's defenses with a round kick, as well as easily toss him through the ceiling with a single arm. He is also fond of incorporating himself into a variety of battle bodies, each possessing widely different arsenals. He is a capable warrior regardless of whatever weapon he wields, whether it be a beam saber, beam claws, or a shield. In nearly every appearance, Sigma is capable of discharging enormous destructive blasts or waves of power capable of covering entire battle areas, and he is a skilled marksman. As the cause of death and suffering for countless innocent lives, Sigma is one of the most dangerous villains in the classic Mega Man universe.



Sigma was created by Dr. Cain as his magnum opus, considered the most advanced Reploid of his time.[3][4] He was put in charge of the Maverick Hunters after their formation, making Sigma the first Reploid in charge of worldwide peacekeeping efforts. He specifically commanded the 17th Elite Unit, leading them to victory many times over the years.

Sigma fighting Zero.

One day, the Maverick Hunters received reports of an overwhelmingly powerful "Red Maverick" that had destroyed an entire unit of Hunters. While investigating, Sigma and his unit tracked the Maverick down to an abandoned laboratory; Sigma decided to confront it alone, so as to not endanger his colleagues. It is here that Sigma encountered Zero, the last product of Dr. Wily. Zero, having suffered a programming flaw from his creation, was uncontrollable, unleashing wanton destruction wherever he went. Sigma was caught off-guard by how powerful Zero was, and suffered heavy damage at his hands. Fortunately, Sigma was saved when a 'W' appeared on Zero's forehead lens, causing him great pain and allowing Sigma to deal the finishing blow by punching him in the head. Either by this punch or by the leakage of a virus from Zero's capsule nearby, the Maverick Virus was transferred directly to Sigma, infecting him.[5]

Following the battle, Sigma ordered the rest of his unit to retrieve Zero's body and contact Dr. Cain for study, limping away in anger. He was later repaired and reassumed control of the Maverick Hunters as usual. However, the Maverick Virus still lingered in his mind - while Sigma's highly-advanced circuitry kept him sane for a while, his thoughts steadily became more and more Maverick over time. The Maverick Virus fused with his mind, mutating into an even more dangerous virus called the Sigma Virus which he held complete control over. Despite this, Sigma seemed to remain stable for months after the lab incident, but still considered the role of Reploids in the world; for example, he noticed the father of all Reploids, Mega Man X, and his dedication to justice, and began wondering how he himself could change the world.[6] Eventually, Sigma came to the conclusion that humanity was merely holding Reploids back from achieving their true potential, and secretly began organizing an anti-human rebellion.

Mega Man X


For more details, see Sigma/Mega Man X.
"Excellent job, X! I see why Zero counted on you. You are almost as good a Hunter as I was. But, the time of your destruction has arrived! You shall regret ever having defied me!"

On June 4, 21XX, Sigma finally puts his plans into motion and leads a mass revolt, declaring war on the humans and all Reploids who support them.[7] Many Maverick Hunters follow Sigma out of loyalty - others, such as Storm Eagle, by force. This leaves Zero, who by this time has reformed and become a powerful Maverick Hunter, in charge of the organization. X agrees to join Zero in the fight, and X and Zero battle through Sigma's Maverick regime together. It is X who finally confronts Sigma alone in his fortress.

When met with X, Sigma first sends his pet, Velguarder, to test his power. Once it is destroyed, Sigma personally confronts him wielding his beam saber. After his body is destroyed, Sigma's leftover head attaches itself to a giant canine machine called "Wolf Sigma".[8] According to the Rockman X Saikyou Daizokan, Wolf Sigma is an incomplete Reploid unto itself, which Sigma then assumes control over.[9]

After Wolf Sigma's defeat, Sigma laments X's decision for siding with humanity, believing that Reploids would have prospered without humanity holding them back.[10] He then perishes in an explosion along with the rest of his fortress. Although his physical body is scrapped, Sigma's "soul" (the Sigma Virus) survives. After the end credits roll, Sigma's face appears on a blue monitor and warns X that he will return.[11][12]

Mega Man Maverick Hunter X

Sigma's role in the remake Mega Man Maverick Hunter X is relatively unchanged. He is vocal about his desire to unleash X's full potential, believing him to be the future of all Reploids rather than an obstacle.[13] His final battle also has some differences: his head willingly detaches from his body to enter Wolf Sigma, he has no lines during his death nor in the credits, and he falls into the tower below during his death animation. Besides the main game, Sigma also featured heavily in the OVA The Day of Σ.

In Vile Mode, Sigma has already started his rebellion and intends to use Vile as a tool to force X to evolve. Rather than follow Sigma's plans, Vile eliminates the commander's lieutenants, and challenges Sigma. Intrigued by Vile's claim to be the true key to Reploid evolution, Sigma invites Vile to try and reach him with the same methods. However, Vile is unable to get the chance to fight Sigma as he was defeated by X and Zero. Sigma finds Vile's broken body afterwards, and questions him in regards to what his motives were; if he would stand as an enemy or kneel and serve. When Vile admits that he isn't sure himself, an unimpressed Sigma orders his men to extract Vile before departing.

Mega Man X2

Neo Sigma in Mega Man X2

For more details, see Sigma/Mega Man X2.
See also: Sigma Virus
"Fine. If you will not follow me, then I'll watch you die once again!"

Just as he promised, Sigma secretly returns and reassumes leadership of his Maverick forces thanks to the intervention of the fanatical X-Hunters. He gains a new body with the help of Serges specifically, becoming "Neo Sigma". He also oversees the "Unification" plot, which focuses on capturing and re-assembling the remains of Zero, whom he plans to reprogram as a loyal killing machine.

After Agile's defeat, marking the end of the X-Hunters, Sigma reveals himself in the Central Computer Stage. Sigma appears alongside Zero to battle X; if X successfully collected all of Zero's parts from the X-Hunters, it will be a Fake Zero whom the real Zero easily defeats for him. If not, X will be forced to fight his friend and incapacitate him, bringing him back to his senses. Afterwards, Sigma announces that he "knows Zero's secret", and that he's destined to serve him. He then flees to the depths of the Central Computer, and Zero opens the way for X to follow him for the final battle.

Neo Sigma battles X with arm-mounted claws and electricity attacks similar to Electric Spark, which he claims in the Japanese version were upgrades. After this first body is destroyed, he assumes his true form, that of the Sigma Virus; this marks the first time Sigma's viral form is seen, as the final boss of the game.[14] X defeats the Sigma Virus, causing him to apparently disappear as the Central Computer explodes. Before he disappears, he taunts X that he will return again and cryptically refers to Zero as "the last of the Doctor's creations."

While Neo Sigma is depicted wearing a cape in official art and the opening of the PSX/Saturn version of Mega Man X3, he is never seen wearing it in his in-game sprites.

Mega Man Xtreme

"Bwah ha ha ha. Your efforts are futile... I will never be defeated! As long as Mavericks exist... As long as evil exists in the minds of humans... I'll come back again and again! X, ZERO... I'll pursue you to the end of the world! Bwah ha ha ha! Farewell! FOR NOW!! Bwah ha ha!"

Targeting the Mother Computer of the Maverick Hunter base, Sigma manipulates a young hacker named Techno and coerces the Shadow Hunters into working for him. His new servants hack the Mother Computer, wreaking havoc and forcing X to enter cyberspace to root them out.

Upon the defeat of Techno and the Shadow Hunters, Sigma reveals himself and faces X within cyberspace. Noticeably more confident than previous times, Sigma taunts X after he is beaten the first time and even calls his defeat at the end of Normal Mode merely a retreat. It is only when he is defeated on Hard Mode that he seems to succumb. However, he implies that he will return as long as not only Mavericks exist, but also as long as humanity retains evil minds.

Mega Man X3

Sigma in Mega Man X3

For more details, see Sigma/Mega Man X3.
"We meet again X... It was easy to corrupt that fool, Doppler. And I would have succeeded if you hadn't interfered. But we are always destined to meet, aren't we X? Let the eternal struggle begin!!"

Sigma resumes his threat when he infects the Reploid scientist Dr. Doppler with the Sigma Virus, who had developed a revolutionary anti-virus to repel the Maverick Virus. He uses Doppler to stage a revolt in Dopple Town, converting the utopian city's reformed Mavericks into his new army.[15] In the disc version, a cutscene plays showing Dr. Doppler building Sigma a formidable new body with the latest in Reploid technology.

Once Dr. Doppler is defeated by X, he feels remorse for his Maverick actions and reveals Sigma's lair under Dr. Doppler's Laboratory. Sigma is hunted by X and battles him with a shield and flamethrower, but is defeated. Sigma then emerges in a heavily-armored form, "Kaiser Sigma" (カイザーシグマ Kaizā Shiguma), to fight him again.[16]

Upon this body's destruction, the Sigma Virus itself appears as a wire-frame head and threatens to possess X's body to replace his own. After chasing X through the flaming base, Sigma finally corners him. If Zero did not end up wounded during the game, Zero appears with Doppler's anti-virus on his saber to erase the Sigma Virus for the time being. If Zero did end up wounded, Doppler appears with the anti-virus on his own body and self-destructs to apparently erase the Sigma Virus.

Mega Man Xtreme 2

For more details, see Sigma/Mega Man X2.
"It seems that I underestimated you... The playtime is over... Now I'll bring this to an end..."

In Mega Man Xtreme 2, Sigma appears in Extreme Mode after the defeat of Berkana or Gareth (depending on if the player is X or Zero), where it's revealed he had planted the seeds leading to the Erasure incident. In a rare instance, he is pleased that X defeated Berkana, claiming that her greed went much too far.

Sigma's first form is the same as his Neo Sigma body from Mega Man X2, but his second form is "Sigma Beast" (シグマビースト Shiguma Bīsuto), a large Ride Armor.[17] The color of his second form is initially orange, but later alternates between blue and red, which can only be damaged by X while he is blue, and by Zero when red. His weak point is the large lion-like face in his chest.

Mega Man X4

Sigma in Mega Man X4

For more details, see Sigma/Mega Man X4.
"Repliforce are the fools this time! Now, all that's left is to destroy Earth with the very weapon they made!"

Sigma was thought to be suppressed forever after receiving the anti-virus created by Doppler, but he still manages to return. Assuming a Grim Reaper-like appearance, Sigma meets with General, the leader of the benevolent militia Repliforce. He provokes feelings of doubt and paranoia of the Maverick Hunters within General, revealing that Sigma's latest plan is to conspire against Repliforce and turn it into a rogue enemy of the world.[18]

In the game's inciting incident, Sigma orders Magma Dragoon to bomb the airborne metropolis Sky Lagoon, killing thousands and causing a rift to form between Repliforce and Maverick Hunters. This rift quickly becomes an all-out war as Repliforce refuses to cooperate and even stages a coup d'état to make a new land for Reploids. During the Great Repliforce War, Sigma allows Magma Dragoon to finally get his chance at a fight with X and Zero, and also has Cyber Peacock and Split Mushroom fight them to test their capabilities. He also sends a sleeper agent, Double, into the Maverick Hunters' ranks, meant to strike when the time is right to destroy the 17th Unit and damage X's trust.[19]

With in-fighting between the Maverick Hunters and Repliforce threatening to destroy them both, Sigma increases his influence over General's paranoia. General, formerly an outspoken advocate of Reploid independence, loses all faith in peace and prepares a satellite attack on the humans, which is Sigma's real intention.[20] Fortunately, X or Zero storm the Final Weapon and stop General before he can turn the weapon's sights on Earth - however, the weapon begins to prepare for attack anyways, revealing that someone else is controlling it.

In the end, Sigma is revealed as the true mastermind. In Zero's story, Sigma reveals a portion of Zero's past involving their first encounter. He then battles X or Zero himself, armed with a new body and a scythe with a beam blade. Once this body is destroyed, he attacks again with a collection of several bodies, including Gunner Sigma (シグマガンナー Shiguma Gannā) and Earth Sigma (アースシグマ Āsu Siguma).[21] After this ultimate defeat, Sigma reveals that the Final Weapon is still ready to strike the Earth - fortunately, General sacrifices himself to stop it from firing. Despite this apparent defeat at the Hunters' hands, Sigma still succeeded in part by destroying Repliforce, and by causing X and Zero to begin doubting their own morality.[22]

Mega Man X5

Psycho Sigma in Mega Man X5

For more details, see Sigma/Mega Man X5 and Sigma Head.
"You'd almost fully evolved to your true self... It's a shame you didn't quite make it, Zero. You had so much potential. Oh well, farewell!'s only you now, X... I will let you live this time. But I won't be so kind next time, and there WILL be a next time! See you soon! You... The strongest Reploid! Bwah ha ha!"

It is some time before Sigma resurfaces again. During his absence, Sigma traces Zero's origins to Dr. Wily, and hatches a plot to unlock Zero's "true" power — the Zero Virus. The first part of his plot involves hiring the mercenary Dynamo to sabotage the space colony Eurasia with a virus and prepare it to crash into the Earth. Once Dynamo is in position, Sigma reveals himself to the Maverick Hunters and heads towards a giant statue while infecting new Mavericks along the way. He is confronted by one of the Hunters, X or Zero, and injures them, while the other shows up later and successfully defeats him.

However, upon Sigma's loss, the Sigma Virus begins spreading all over the Earth faster than ever. The entire world is thrown into a panic, but to make matters worse, Dynamo sends the Eurasia colony on a collision course with the Earth too. This combination overwhelms the Maverick Hunters, and regardless of their efforts, large pieces of the colony still hit the planet, causing massive damage and revealing a new virus called the Colony Virus. This virus mixes with the Sigma Virus, synthesizing the Zero Virus and forming an energy-based area called Zero Space wherein Sigma hides.

This was part of Sigma's ultimate goal: to form the original Zero Virus, intending to make Zero "remember" who he is and revert to his original, intended programming. Despite the creation of the Zero Virus and the ensuing battle between X and Zero, Sigma ultimately fails in this endeavor, as both X and Zero still manage to defeat him in both of his new bodies, Psycho Sigma (サイコシグマ Saiko Shiguma) and the gargantuan Final Sigma W (ファイナルシグマW Fainaru Shiguma W).[23]

In the aftermath of the battle, Zero's severed torso lies dormant on the floor. X picks Zero up and tries to get him to respond. The remains of Sigma's head lying nearby suddenly become active and fire an energy laser directly at X and Zero, hitting both of them in the chests. As Zero's body falls from X's grasp, he manages to fire one last blast from his Z-Buster and finishes Sigma. X is critically wounded in the battle, both from the battle itself and Sigma's final attack (the force of the laser being so strong that it ripped through his entire lower half and arms), but he is miraculously repaired (the cutscene suggesting that it may have been by Dr. Light's hologram) and returned to the Hunters.

Mega Man X6

Sigma in Mega Man X6

For more details, see Sigma/Mega Man X6.

Three weeks pass as the human population moves underground to survive the devastation and pollution left by Sigma's last attack. Meanwhile, a renegade Reploid scientist, Gate, plans to use a newfound power known as the Nightmare to create a world of only the highest, most powerful Reploids. However, as a failsafe he also uncovers Sigma's remains and rebuilds him, keeping him in his Secret Lab as a last resort weapon. Due to the stress of spreading the Sigma Virus during the "Colony Incident", Sigma's programming is damaged beyond what Gate can repair, and he is reduced to a half-conscious and barely-functioning wreck of his former self. He seems to remember little more than his rage toward X and Zero and speaks in a garbled voice, rarely able to form sentences. Additionally, Gate's work on Sigma's new body is unfinished by the time he appears.

Upon his defeat at the hands of the Maverick Hunters, Gate reluctantly releases Sigma to attack them. However, Sigma refuses to cooperate and spitefully kills Gate before challenging the Hunters to face him deeper within the Secret Lab. They pursue him and he attacks using his incomplete body, but is defeated. After this first form, Sigma emerges as a gigantic unfinished body with a skeletal appearance named Hell Sigma (ヘルシグマ Heru Shiguma), and is again destroyed.

Mega Man X7

Head shot of Sigma's first form.

For more details, see Sigma/Mega Man X7.
"That's right, folks! I'll do it again, and AGAIN! I will make X AND Zero MINE! Now, come and get me! Give me a good fight, like you always do!"

After hearing of Red Alert's success in recovering the Virus Program Σ-02 from Cedar and Aluce, Sigma decided to get in contact with the vigilante syndicate for his next plan.[24] Sigma met with Red, this time under the alias of "The Professor", and informed him of his plan to use the mysterious Reploid Axl to copy the DNA programs of X and Zero for immense power boosts. Before putting this plan into motion, he proved his worth to Red by using the DNA Axl took from other Reploids to give power boosts to Red and his colleagues first. Many of the Reploids whom Axl was made to target to make DNA powerups were mostly innocent, irking Axl. This ended up helping him realize something was going on, and it prompted him to seek asylum with the Maverick Hunters.

This forced Sigma to find a way to bring Axl back into Red Alert's service. He secretly infected the eight Red Alert generals, blackmailing Red into following his orders and challenging the Maverick Hunters for custody of Axl. Once all eight of Red Alert's generals were defeated by the Hunters, Red leaked them the location of the Crimson Palace, which they then infiltrated. The Hunters fought Red, but he self-destructed out of grief and shame for his actions, and in order to keep himself from being further manipulated by Sigma.

Afterward, the Hunters continued on to confront Sigma, who was excited to see his old rivals again. After they defeated both of his forms, Sigma reappeared once more (appearing similar to his first form in Mega Man X6) and punched Axl through a wall before vowing to X and Zero that he would again return in a new body. Red, who had presumably died, suddenly reappeared, and Sigma attempted to possess him and regain his strength. However, Red revealed himself to actually be Axl copying Red's form, who then proceeded to blast Sigma out of a window.

Unusually for most games in the X series, Sigma is never identified by name.

Mega Man X8

Sigma in Mega Man X8

For more details, see Sigma/Mega Man X8.
See also: Copy Sigma
"Your dedication to what you refer to as "justice" is what first got me thinking... I realized the imperfection of this world, and decided I must change it."

Sigma reappears for presumably the last time during the Jakob Project. A new generation of Reploids goes into production, each containing advanced Copy Chips that give them complete immunity to Maverick compromises such as the Sigma Virus. X witnesses this first-hand when an elevator car full of Reploids crashes at the Jakob Orbital Elevator, and he finds the car is full of Reploids who copied Sigma's durable frame to survive the impact. Lumine assures X it is a safe process, but X is still bothered by it.

Soon after the new generation Reploids begin their riot, Alia discovers that their Copy Chips also bear Sigma's program - not just his body's DNA, but his actual program data. This confirms Sigma's involvement in the uprising. It appears the new generation Reploids are well aware of Sigma's influence and entirely willing to work for him; their relationship is like that of a father and his children.

After the Maverick Hunters defeat the eight major new generation Reploids, Sigma personally contacts Hunter Base. He announces that he and his kind are fleeing to space to leave the old world behind, daring the Hunters to pursue him via Jakob. Once the Hunters arrive in Gateway, they confront what appears to be Sigma himself - however, defeating it reveals it was just a Copy Sigma.

Alia locates a Sigma Palace on the surface of the Moon, and the Hunters head there. Once one of them reaches the throne room (the other having been separated by Vile's attack), Sigma welcomes them in an incomplete body; this body is stronger than any of his previous forms, though it has a weak point in the chest.[25] He tells X his unique mind is what first inspired his ambitions, thanks Zero for giving him the Maverick Virus, and calls Axl a worthless prototype. Sigma then strikes, and is able to immobilize the Hunter present as he gloats in victory. However, the other Hunter arrives just in time to save their partner, and the two work together to defeat Sigma. The Maverick explodes, reduced to a pile of rubble.[26]

Suddenly, Lumine appears and congratulates the Hunters for defeating Sigma. He explains that he was using Sigma's ambition to help advance the new generation Reploids' move to space, and now he can dispose of the older Reploids such as X, Zero, Axl, and even Sigma as well, for they are not needed in the new world. The Hunters fight and defeat Lumine, but in his final moments he makes a startling claim: Sigma was destroyed for good and could no longer be resurrected.

It is believed that the reason Sigma would not regenerate after this defeat is because he was on the Moon, where the lack of available bodies to possess and the vastness of space may have weakened his Sigma Virus to deletion (his defeat in space in Mega Man X4 occurred on a space station; the fact that Sigma didn't seem frustrated about this defeat implied he could escape). Additionally, the immunity of new generation Reploids to viruses meant that he could not possess any of his minions on the Moon, nor much of the population on the Earth. Sigma expressed uncharacteristic disbelief when X, Zero and Axl defeated him on the Moon, showing he may have been aware this was his final demise. However, having passed on his data to new generation Reploids who can turn Maverick without remorse, Sigma's dreams of extremism and Reploid evolution are primed to live on into the future.

Post-Mega Man X series

Although Sigma himself never returned in person, the Sigma Virus still lived on and would plague the world until the discovery and creation of the Mother Elf from enzymes in Zero's body. X then utilized the Mother Elf to fully neutralize the Sigma Virus, bringing a permanent end to the Maverick Wars that Sigma had started. Unfortunately, this series of events would later lead to the far more destructive Elf Wars, due to Dr. Weil's radical agenda to punish the Reploids for the damage caused in the many conflicts during the Maverick Wars.

Other game appearances

Sigma in Project ✕ Zone 2
  • Sigma shows up briefly on the green monitors of the Mega Man X: Command Mission opening cutscene, which shows some scenes from the Mega Man X7 ending.
  • In Rockman Xover, Sigma, along with Dr. Wily and other villains from other Mega Man series, join forces to wreak havoc. He is the boss from World 2 and World 7, and appeared in several Battle Memories.
  • Sigma, with his appearance from Mega Man X4, is one of Chuck Greene's costumes in the Dead Rising 3 DLC mode "Super Ultra Dead Rising 3' Arcade Remix Hyper Edition EX Plus α". He attacks with his scythe and laser eye, and has a special attack called "Sigma Crusher".
  • Sigma appears as a Spirit in Super Smash Bros. Ultimate with his appearance from Mega Man Maverick Hunter X. He is an Attack-type Primary Spirit in the "Ace" class. In Adventure Mode, Sigma is found guarding Mega Man. The playable character representing him is Ganondorf, and the theme music is X vs. Zero from Mega Man X5 and Mega Man X6, alluding to how Sigma largely instigated X and Zero's fight in the former game.
  • Sigma appeared as an Unit Card and in the illustrations from some Action Cards in TEPPEN.

Yamato Man

  • Sigma appeared as an event character in the Japanese version of Zombie Cafe.
  • In the Rockman X DiVE event from the Taiwanese version of Shironeko Project, a Sigma Virus left the Rockman X DiVE cyberworld and went to the Shironeko world, mutating into Sikuma (romanized as SIGUMA and SIKUMA in the game). He is the final boss from the event story, and the event's co-op boss, being fought in a form similar to the Sigma Head from Mega Man X5.

Yamato Spear

Mega Man X DiVE

Sigma appeared both as playable Hunter Programs and as bosses.

  • Sigma is a S rank Hunter Program whose Active Skills are Dash Blade and Head Beams.
  • Sigma (X4 2nd form) is a DiVE Festival exclusive Hunter Program whose Active Skills are Scythe Throw and Laser Eye.
  • Sigma has a S rank Halloween version named Halloween Sigma. His Active Skills are Penta Bat Shot and Hellfire Dust.
  • Sigma's many forms appeared as the boss from the Raid Boss and Guild Boss events. In order of appearance: Wolf Sigma, Sigma (X4 1st form), Sigma (X4 3rd form), Final Sigma W, Sigma Virus, Hell Sigma, and Sigma (X3 1st form). Some of them also appeared as event bosses.
  • Sigma is the boss from the Monster Hunter Rise collaboration event stage Mission Code: R・I・S・E, where Wolf Sigma had its data mixed with a Magnamalo and became Magnamalo Sigma.

Marvel vs. Capcom: Infinite

See also: Ultron Sigma and Ultron Omega

Sigma appears with his original form from Mega Man X as a downloadable playable character, and appears in the story mode as part of an antagonist tag team alliance with Marvel Comics' Ultron. His default design is derived from his appearance in Mega Man X, though he implies that it was only one of several forms he had taken and was not particularly fond of this form. His Premium outfit is his Final W from Mega Man X5. His move set makes use of his beam saber with specials like Arc Divide, swinging in multiple broad arcs, each slash producing patches of corrupted data that further damages the enemy and Straight Divide, based on his airborne dash from Mega Man X. New to his arsenal is Reflector Magnum, which fires missiles from his fingers that bounce off of floors and a Counter Teleport where he teleports behind the opponent after parrying a physical attack. It can also be used to reflect projectiles. His Hypers are Doom Buster, firing a large ball of fire in front of him, Blazing Line, which has him jump into the air and shoot a traveling laser that rakes the ground with large explosions and Rave Divide, a series of powerful slashes with his saber. His Lv. 3 Hyper is Final Sigma wherein he grabs the opponent's face and transports them into a digital world where wireframe copies of himself unleash a barrage of brutal attacks, ending with them skewering the victim and returning them to the physical world, his hand still grabbing their face. When Thanos and Ultron go to Abel City to obtain the Infinity Stone that was with Sigma, Ultron and Sigma decided to form an alliance, with Sigma allowing Ultron stab his body with his hand (with Sigma suggesting they do so via that method instead of Ultron's original plan of utilizing violence alone), armed with Reality Stone to upload his mind into Ultron’s body, becoming a singular being known as Ultron Sigma and betray Thanos as part of their mutual agenda to wipe out all organic life. After defeating Thanos with their combined powers and taking the Space Stone from Thanos, Ultron Sigma using both Reality and Space Stones to transform Ultron’s body into their current primary appearance of Ultron Sigma form, and fuse their worlds. After Dante managed to trick Ultron Sigma into destroying themselves with the Soul Stone, they ended up mutating into a massive form known as Ultron Omega from that Stone’s full potential side-effect, before being finished off for good by the heroes as well as X and the Infinity Buster.

Other media

Mega Man (Ruby-Spears)

Sigma in the Mega Man cartoon show.

Though not a starring character, Sigma was referred to in the episode Mega X of the Ruby-Spears Mega Man animated series, where X, Vile and Spark Mandrill go back in time. Vile and Spark Mandrill's goal was to obtain lightanium, which was worth a fortune in the future and could be used to fund Sigma's rebellion. His profile, shown by X, shows him in his original body and mistakenly spells his name as Cigma. The only line Sigma has is when Vile contacts him near the end of the episode — a short praise: "Well done, Vile."

Mega Man (Archie Comics)

Main article: Sigma/Archie Comics

Sigma is the main antagonist from the Mega Man X era and the Worlds Unite crossover.

Rockman X

Sigma starts a rebellion against humans, beginning by killing a Maverick Hunter, Kyle, that was against him, and convincing various Hunters to join him by saying that Reploids are superior to humans and they should no longer take orders from them.

When Spark Mandrill was giving up the fight against X with fear and saying he would tell all of Sigma's plans to him, Sigma uses a giant hologram of himself (via a flying mechanism) to kill Spark Mandrill and talk with X. Before the fight against Armored Armadillo, it's shown that Sigma scarred Armadillo's left eye because he didn't follow his orders to defeat X in the forest. After defeating the eight Mavericks, Sigma appears and challenges X to fight him in his fortress. Although the battle is difficult, X manages to defeat Sigma. Sigma then uses a giant body that is too powerful for X, but he manages to destroy him by crashing his fortress.

In Rockman X2, Sigma is shown to have survived the event and starts working on a more powerful body. Still, after the defeat of eight Mavericks and the X-Hunters, Sigma is defeated by X and Zero.

In Rockman X3, Sigma took control over Dr. Doppler to start another Maverick uprising, using him to infect several Reploids with "Worms" and create a more powerful body by analyzing X. He has a fierce battle against X, but he is eventually defeated by X with Zero's saber. However, he reveals a more powerful body, Kaiser Sigma, and manages to destroy X. To Sigma's surprise, X regenerates and his armor became golden, and he uses his new power to destroy Sigma. Sigma also appeared disguised as an angel when a worm infected by X, who told X the latter can't enter paradise due to "sins" in an attempt to cast doubt into him, although X eventually saw through the illusion and shot Sigma.

Sigma only has a cameo appearance in the Rockman X4 manga, being mentioned by Double in the last chapter where he makes clear he had been the true cause of the Great Repliforce War.

Irregular Hunter Rockman X

Sigma appears as the leader of the Maverick Hunters. When Storm Eagle challenges X to a fight, Sigma appears and stops Storm Eagle without destroying him, giving him a lecture and the Storm Tornado to X. However, when Zero starts acting strangely, Sigma tells Armored Armadillo that Zero became a Maverick and orders him to destroy Zero. Later, Vile escapes from his cell and takes four Hunters to work for him. After the defeat of the four Hunters, Sigma orders X to go after Zero and destroy him, but Zero reveals Sigma's involvement in the events, and they are attacked by Vile, Storm Eagle, Armored Armadillo, and Boomer Kuwanger. After the defeat of the latter three, Vile escapes and Sigma decides to destroy the base of the Maverick Hunters. After talking with A-1, X and Zero go after Sigma, who started attacking the city with several Mechaniloids. Sigma appears to face the two Hunters, but after being hit by two charge shots at the same time, He calls Vile and shows that they took A-1 as hostage, taking advantage over X. Unable to see X taking so many hits, A-1 releases himself and runs to Sigma, self-destructing near him. Sigma is stunned by the explosion, and X, angry and sad for A-1, fires a large charge shot, and Zero also fires one at the same time, but Vile saves Sigma and they escape. While leaving, Sigma tells them that he will surely conquer the world.

Rockman X The Novel: Irregulars Report

X8NavigatorAlertIconEdit.png This section requires expansion.

Sigma was created by Dr. Cain as his masterpiece. However, upon investigating the ruins where he fought against a Maverick Zero, he discovered the truth about X and the Reploids and was filled with hatred for being simply a copy of X, which led to his plan to rebel against humanity and test X's abilities.


Main article: Sigma/Gallery


See also


Early designs that served as the basis for Sigma, and later the X-Hunters.

  • Sigma was designed by merging three early villain designs created by Inafune during the early development of the first Mega Man X game. The same designs were later used as the basis for the X-Hunters in Mega Man X2.[27]
    • Sigma's face has a close similarity to both M. Bison and Sagat, two major villains of the Street Fighter series. He also resembles Braiking Boss, the villain of Casshern. Due to this, some fans believe that Sigma was based on one of them.[28] The resemblance to M. Bison is even referenced in Project X Zone 2.
    • During a 2008 Q&A session, when asked if Sagat served as inspiration for Sigma, Keiji Inafune stated that Sigma (and Zero) represent the idea that nothing is absolute.[29]
  • Sigma (Σ) is the 18th letter of the Greek alphabet and is used in mathematics to denote series, finite, or infinite sums of variables. The Σ symbol is often seen on Mavericks from Sigma's army. Interestingly, the sigma (Σ) letter was originated from the Phoenician letter sheen (W), which is similar to the English letter "W".
    • Commentary by Keiji Inafune on concept art for Sigma made it clear that Sigma's connection to Dr. Wily was intended from the start.[30]
  • The penultimate cutscene of Zero's story in Mega Man X4 reveals Sigma's pre-Maverick design, which lacked his facial scars and the spikes on his wrists and knees featured on his original design. This design would be maintained for his pre-Maverick appearance in Maverick Hunter X, with redesigned wrist guards. The single-frame flashback of this battle from Mega Man X5, however, discards the redesign, instead using the standard Maverick Sigma design without facial scars.
  • There are multiple interpretations of the way Sigma received his trademark eye scars:
  1. In Mega Man X4, the Maverick Zero inflicted damage on Sigma's face resembling his future scars. It is unconfirmed if he retained the scars from this encounter, or mimicked them upon going Maverick.
  2. In Mega Man Maverick Hunter X's OVA, The Day of Σ, X scarred Sigma's face with his bare hand during their first confrontation. Later as Wolf Sigma, Sigma's damaged face ironically resembles the wounds he received from Maverick Zero in Mega Man X4.
  3. In the Rockman X manga, Sigma scarred himself as a mark of going Maverick, using the heat of his fingertip guns after shooting Kyle.
  4. In Rockman X The Novel: Irregulars Report, Sigma's scars were also implied to be self-inflicted. While communicating with Zero, Sigma is seen putting his right hand near his eyes, with his fingers having traces of Reploid blood on them.
  • Mega Man X and Mega Man X3 are the only games to have official artwork for Sigma's final forms in their respective games.
  • If Sigma's name is entered as the player's name in Mega Man 9, the game erroneously says that it is "inappropriate language", and changes it to "Si**a".
  • Although Sigma is never seen in the Mega Man Zero series, the Sigma Virus is mentioned in Mega Man Zero 2 and Mega Man Zero 3, and in the first game his symbol is visible (though difficult to spot in the background) in the left of the chamber where Zero was resting. Sigma also makes a cameo in the Rockman Zero manga,


  1. Mega Man Homepage - X Characters. Retrieved on 2006-August 6.
  2. Mega Man Maverick Hunter X, Capcom (2006)
    The Day of Σ Scene 2 Hunter Base
    Sigma: As far as [Mega Man X's] judgement and abilities on the battlefield is concerned, he has shown tremendous promise. However, he tends to hesitate when the situation calls for decisive action. // Dr. Cain: He worries too much. Course, that is his greatest feature. And the source of his potential. Sigma, you don't have that problem at all.
  3. Compendium of Rockman X page 15
  4. Rockman X Chouhyakka page 46
  5. Story summary from Rockman Zero Collection official site. (Translation in The Mega Man Network)
  6. Sigma: Your dedication to what you refer to as "justice" is what first got me thinking... I realized the imperfection of this world and decided I must change it. - Mega Man X8.
  7. "The Journal of Dr. Cain", Mega Man X instruction manual, 1993. Page 10.
  8. R20 Rockman & Rockman X Official Complete Works, page 125.
  9. "A yet incomplete extra large wolf type repliroid. Sigma's head takes over the functions of the brain, but because of its excessive size, the feet and arms require more development time to be completed. Once the super-powered repliroid is completed, Sigma will be unstoppable in his plan for world domination!" - Rockman X Saikyou Daikozan
  10. Sigma: Why, X?! Why have you done this to us?! Without the humans, my Reploid brothers could have ushered in a new age.....
  12. 「おまえがたおしたものは、わたし じしんではない。バラバラになったキカイは、わたしの ぶんしんのようなもの。わたしはふたたび、じったいとなってよみがえる・・・ エックスよ、また あえるひをたのしみに しているぞ。ハハハハハ・・・」 Translation: "What you've destroyed, is not my true self. The scattered machine, is something like my avatar. I will become substantial once again... X, I am looking forward to seeing again. Ha ha ha ha ha ..." --Rockman X game, 1993 (Japan)
  13. Sigma: Magnificent, X! And to think you've been classified as a "B-class" hunter! Ha ha ha ha!
    X: Sigma! Your Maverick plans stop RIGHT HERE!
    Sigma: Mwah ha ha! Hah ha ha ha ha ha!
  14. Mega Man Homepage - Mega Man X2: Bosses. Retrieved on 2007-8-6.
  15. Mega Man Homepage - Mega Man X3: Characters. Retrieved on 2007-8-6.
  16. Mega Man X3 ending.
  17. Compendium of Rockman X page 137
  18. Sigma: Hee hee hee. My plan to keep Repliforce and the Maverick Hunters at each others' throats worked perfectly! --Mega Man X4 1997 (US)
  19. Mega Man X4
    (Something beeps from within Double, and he presses on a panel on his chest. A mysterious voice is then heard.) // Mysterious Voice (Sigma): It's me! Those hunters must not be allowed in here! Terminate them!! // Double: Roger... (turns back to the Hunters)
  20. General: ...We're going to build a nation for the Reploids. That's our ultimate goal. We'll fight anyone who tries to interfere with our independence. --Mega Man X4 1997 (US)
  21. Mega Man X Legacy Collection
  22. Mega Man Homepage - Mega Man X4: Characters. Retrieved on 2007-8-6.
  23. Mega Man X Legacy Collection 2 Hunter Medals and X Challenge
  24. Rockman X7 Original Soundtrack booklet
  25. Rockman X8 Hisshou Kouryakuhou - pp. 117-119
  26. Sigma Palace, Mega Man X8. (Normal or Hard Mode).
  27. Mega Man X Official Complete Works, UDON Entertainment Corp. 2009. pg.93. Retrieved on April 8, 2011.
  28. The Reploid Research Lavatory: A Day For Sigma
  29. "Some people think he might have been inspired by Sagat from Street Fighter because of his look, but that's not actually the case. Sigma and Zero basically represent the idea that nothing is absolute. Sigma was a powerful leader of the Maverick Hunters but after Zero passed the virus to him, his allegiance changed. Circumstances can change anything, and nothing is absolute." --Keiji Inafune, 2008. Capcom-unity - Inafune-san Answers Your Questions!
  30. "The connection with Wily had always been part of the plan." - Sigma concept art, Keiji Inafune, Mega Man X Complete Works