Zero made his debut appearance in "Mega Man X" in 1993, and a cameo appearance in '. In the latter, Zero was revealed to have been originally created by Dr. Wily sometime during the "Mega Man" series. Zero works as a Maverick Hunter, a soldier in charge of defeating Mavericks, robots who turned against humanity. He plays the role as X's comrade and best friend in the "X" series. The two, later accompanied by Axl, fight Sigma, Vile, and other enemies throughout the series. While in the first two titles he only assists X during gameplay, he becomes an playable character in "X3", but is limited in gameplay. Zero debuts as a fully playable character in "Mega Man X4" making him one of the two playable characters along with X. In his scenario, Zero is haunted by nightmares of a shadowy figure (implied to be Wily) awakening him and giving him orders to destroy an unknown individual, and visions of ensuing carnage. Additionally, during his scenario, Sigma reminds him of the time that he led the Maverick Hunters, and the encounter between the two that led to a vicious battle that led to Sigma punching out the crystal on Zero's helmet, leading to Sigma later becoming infected with the Maverick Virus. Depending on the story development, Zero can be fought as a boss character in "Mega Man X5". In "Mega Man X6", Zero is not initially present in the game since he was presumed dead at the end of "Mega Man X5" during a fight against Sigma, but he becomes an optional character depending on how the story develops throughout the game. Zero is one of the two initially playable characters in "Mega Man X7", along with Axl, and Zero also appears in "Mega Man X8" as a playable character along with X and Axl. In the spin-off title "Mega Man Xtreme", he is an assistant character but becomes playable in the sequel, "Mega Man Xtreme 2". He is also playable during the prologue and the last chapters from the role-playing video game '.