10 Video Game Bosses Who JUST WOULDN'T DIE

When a sentient android called Mega Man X is unearthed in the future, he finds himself caught in a war against Maverick robots, led by the ruthless android, Sigma.

Though Sigma was once a noble warrior, he was driven insane after being infected by the Maverick virus. On top of that, his programming mutated the malware into the Sigma Virus, allowing the cleft-chinned tyrant to transfer his consciousness into any machine in his proximity. Every time Sigma is destroyed, he hides his essence in a nearby computer or robot, allowing him to rebuild his body.

Due to his pseudo-immortality, X and his allies have squared off against the megalomaniacal evildoer more times than they can count. On multiple occasions, Sigma is seemingly destroyed, only to be reborn in a new body seconds later, forcing the Blue Bomber to clash with him two or three times in a row.

Now, Sigma seemingly met his end in Mega Man X8, and hasn't appeared in an official instalment in decades. But if the X series was revived, it wouldn't be surprising if one of the characters said, "Somehow, Sigma returned."