The first reploid developed by Dr. Cain by studying the hardware of Mega Man X. He was the head of the Maverick Hunters, a group of reploids dedicated to destroying reploids who had gone maverick and were now attacking humans. During a fight with Zero, he contracts the Maverick Virus, which turns him Maverick and, due to his unusual circuitry, morphs into the Sigma Virus. The Sigma Virus allows him to control other reploids.

After turning Maverick he becomes the main antagonist for almost all of the Mega Man X games.