Age of Apocalypse
In a twisted version of the world they knew, the X-Men battle against the eternal mutant Apocalypse as Bishop seeks to repair the timeline. Legion, Xavier's own son, attempts to kill off all of Xavier's enemies; however, when Legion attempts to murder Magneto, Xavier sacrifices his own life to save Magnus. As a result, Magneto casts off his anti-human sentiments and carries on Xavier's dream of peaceful co-existence, thereby founding the X-Men.