History
Apocalypse was a mutant who in believed in survival of the fittest. He founded his own group called the Followers of Apocalypse who also believe in survival of the fittest, and with this group he planned to gather the strong and eat the weak. He recruited the mutants called Gideon and Candra after they betrayed the Hellfire Club, and led the Followers on their attack on the X-Men in Washington.
During the attack Apocalypse was challenged by Charles Xavier. He appeared and lifted Xavier out of his hoverchair, Charles tried to fight back mentally, but Apocalypse stated that both his overwhelming power and vast vestments were blocking/damping Xavier's from affecting him or his followers. Apocalypse was about to run Xavier through, until a Phoenix Force empowered Cyclops striked Apocalypse down, giving Jean, who was also empowered by the Phoenix Force, the chance to pull Xavier away with her telekinetic powers.
While Scott was flying Xavier to safety, Jean faced Apocalypse. Unfortunately, Apocalypse matched her blow for blow with his damping ability, while Xavier, having been dropped by Cyclops after he was hit by Gideon's plasma rifle, was crawling up behind him. Xavier used the last inch of his power to finally break into Apocalypse's mind and stamp on it, killing them both.[1]