Scott Summers, a.k.a. Cyclops, was rescued from the "foster care" of Jack Winters, a mutant criminal known as the Jack O'Diamonds, and enlisted by Xavier as the first member of the X-Men.

Cerebro first appeared in X-Men #7 (September 1964). It was created by Professor X and Magneto, and was later enhanced by Dr. Hank McCoy.

In a strange town near the Himalayas, Xavier encountered an alien calling himself Lucifer, the advance scout for an invasion, and foiled his plans. In retaliation, Lucifer dropped a huge stone block on Xavier, crippling his legs.

Writer Scott Lobdell established Xavier's middle name to be Francis in Uncanny X-Men #328 (January 1996).

Xavier formed a psychic bond across galaxies with Princess Lilandra from the Shi'ar Empire. When they finally met, it was love at first sight. Later, when she was crowned Empress, Professor X became her trophy husband.

Charles and his stepbrother Cain Marko served in the U.S. Army and were stationed in Korea where Marko found a hidden temple dedicated to the entity Cyttorak. On entering, Marko discovered a jewel that transformed him into the Juggernaut.

Joining Lilandra in her cause to overthrow her sister Deathbird, Xavier took on the powers of Phoenix temporarily wherein he was nicknamed Bald Phoenix by Corsair.

During a battle between the X-Men and Magneto's Acolytes, Professor X used his telepathic powers to shut down Magneto's mind and render him catatonic. During the psionic contact, the darkest aspect of Magneto's mind escaped into Xavier's subconscious, where it "merged" with Xavier's own darker nature to create the being known as Onslaught.

Xavier earned PhDs in Genetics, Biophysics, Psychology, and Anthropology with a two-year residence at Pembroke College, Oxford University. He also received an M.D. in Psychiatry while spending several years in London and was later appointed Adjunct Professor at Columbia University.

At graduate school, Professor X met a Scottish girl named Moira Kinross, a fellow genetics student with whom he fell in love. But when he left to fight in the Korean War, she broke off their engagement and instead married her old boyfriend Joseph MacTaggert.