Sigma is the main villain in the Mega Man X franchise. He is equivalent to Dr. Wily in so many ways despite being defeated he always comes back to menace the world. He is the arch-enemy of Mega Man X, Zero and later Axle. Sigma is often regarded as one of the top video game villains. I'am going to go into more details about Sigma.

Dr. Cain discovers X he uses X's design and creates Reploids. Reploids are human like robots that can make choices on their own. They can also show emotion just like the humans. However, some Reploids go rogue. The Maverick Hunters are formed to destroy would be rogue reploids. Dr. Cain creates Sigma his finest reploid. Sigma is the leader of the Maverick Hunters. He leads them to victory several times. Sigma and the maverick hunters put down rebellions. Dr. Cain states he does not worry about Sigma going maverick because he contains Cain's new circuits and programming. In the meantime Sigma meets X who quickly rises in the Maverick Hunters. He sees that X has great potential.

At sometime Sigma is called to deal with Zero, who at this time was a Maverick. Zero activated from Dr. Wily's old lab. Zero wiped out several Maverick Hunter units. Sigma and Zero engage each other in a long bitter fight. Zero technically defeats Sigma. Before Zero can finish Sigma off a W starts glowing in Zero's jewel on his forehead. Sigma smashes it knocking out Zero. He takes Zero back to the Hunters.

It was revealed that Wily had installed a virus in Zero that made him very violent. This Virus left Zero and entered Sigma. The virus starts merging with Sigma's programming becoming the Sigma Virus. At first it appears Sigma was okay after the bitter battle. Zero due to the virus leaving his body has become a high ranking Maverick Hunter and close friends with X. Zero is second in command among the hunters.

Suddenly Sigma goes Maverick and takes almost all of the Maverick Hunters with him. He launches attacks on the world. He also says that Humans should be eliminated or enslaved. He is making a world for reploids only. He starts to spread his virus making other reploids come to his side. The virus is quickly dubbed the Sigma Virus.

X and Zero are the only two hunters left that can stop him. Zero is now the commander of the hunters while X is second in command. Together they put down Sigma's rebellion.

Sigma though was not done. He reveals to the hunters that his programming will allow him to build new bodies and he will be back.

In Mega Man X2 his true form is that of a computer virus. He builds a new battle body. He uses the computer base to spread his virus. He is able to infect more reploids. He also tries to rebuild Zero to make Zero become a maverick again. However, he is foiled by X. Zero is rebuilt and helps X defeat him. Sigma reveals that he knows Zero was one of the Doctor's last creation

In X3 Sigma returns once again using his true computer virus form to infect others. He not only infects Doppler but manipulates him into creating powerful mavericks. He also manipulates Doppler into creating him a new powerful battle body. At the end though he is stopped by the Maverick Hunters. Doppler had come out with a virus. Zero uses it to take out Sigma.

In X4 he shows how ruthless he is. He infects Mavericks of course but he shows how very manipulating he can be without even infecting. He states a false flag operation. This puts Repliforce and the Maverick Hunters against each other. Both armies fight each other nearly destroying each other. Sigma sets back and watches the carnage before truly revealing himself. He lets X and Zero know how they killed their friends in battle. To make matters worse he built a deadly weapon to fire on the humans.

In X5 he shows again how ruthless he is. He sends a space colony into Earth's orbit in hopes of crashing it. In the meantime he loses to the hunters on purpose just to spread his virus. He gains a new ability to use old data. Here he even comes into contact with Dr. Wily through computer data. His plain is to use Zero to spread the virus. He is stopped of course but not before destroying thousands of people and reploids.

In X6 he is revived by Gate. Gate became infected when he touched one of Sigma previous parts. Sigma reveals that he did not need gate that is programming allows him to come back again and again. Although it is shown it takes him awhile to rebuild. In X6 he was basically a zombie.

In X7 he manipulates Red and his organization into taking on the Maverick Hunters. He plays on the distrust the organizations have each other. Again very similar to the events of X4.

In the last game X8 he shows he has a new ability to infect reploids. The new reploids can copy data including sigma bodies. This means Sigma's data is already in them. Therefore his data is able to merge with the new generations's reploids. He calls the new reploids his children. Here he wants to create a New World and destroy the entire planet. He is defeated in space. X, Zero and Axle wonder if the virus will now die out since there is nothing to infect in Space. On the other hand, his virus survived Mega Man X4's battle which also took place in space.

Sigma is a very ruthless villain. He does not care who he takes with him. He is very manipulative. In addition, his is a very powerful opponent. His new forms become more powerful. It is also evident he becomes more insane each time he is defeated. This is evident when he sends a colony to crash into Earth, and tries to destroy the entire planet. His true form allows him to regenerate despite being defeated over and over again.

His virus is shown to have multiple ways to infect others. One way is the virus rewrites the programing. This makes the infected reploid insane. Moreover, he can cause the virus to rewrite a reploids DNA causing mutations. Once again making the infected reploid a dangerous being. He also uses the virus to merge with the reploids existing programming. Finally his virus deletes programing and replaces it with his reprogramming.


Sigma though does have some weaknesses. He appears to be weak to weapons that generate electricity or static. This would make sense since his true form is that of a computer virus. He is also weak to anti virus vaccines like Doppler created. But this only takes him out temporary as he is able to come back.