Charles Xavier is a telepathic mutant. He started a school for young mutants that taught them how to use their powers for good. When he discovered he had telepathic powers, he began to become fascinated with mutant abilities. He also met a young Mystique, who he let live in his mansion. As a young adult, he met another young mutant named Erik Lensherr (who would later become Magneto) who was also discovering his powers. They were best friends until they decided to go their separate ways. His relationship with Mystique was also strained by this, as she left to join Magneto's brotherhood. Xavier then later founded the X-Men with his first five pupils: Cyclops, Iceman, Archangel, Beast and Jean Grey (who joined in that order).