The Birth: Charles Xavier was a mutant by birth. Charles' telepathic powers began emerging when he was still a boy, and as he grew older he learned to control them. Later, he would be called as Professor X - the head of the school for gifted youngsters.
Prof. X made his first debut in X-Men #1, September 1963 going against Magneto.

The Alter Ego: Charles Francis Xavier is the son of nuclear researcher Brian Xavier and his wife Sharon. After Brian Xavier's death, Sharon married his colleague Dr. Kurt Marko, whose had son by a previous marriage named Cain Marko. Kurt abused Sharon, making Charles regret not being able to help her as he was only 10. His powers sprouted not much later, and using his own in-born genius (along with some telepathic assistance), received his Bacholers Degree at 18. He then went to Oxford, where he first met a Scotswoman; Moira MacTaggart. He had a crush on her, but decided to go into the armed services after getting his graduate degree. While serving alongside his step-brother, Cain Marko, the two were seperated from their platoon, and ended up in some sort of temple. It was there Marko got the Crimson Gem of Cytorrak, and became the Juggernaut. After he returned to Moria, she called off their engagement. Depressed, Xavier started travelling around the world. Xavier went to Israel, where he fell in love with Gabrielle Haller and became friends with a man calling himself Erik Magnus Lehnsherr. Lehnsherr would years later become his greatest enemy and rival, Magneto. Xavier was unaware when he left Israel that Haller was pregnant with his son, who would become the mutant known as Legion.
His first appearance was in Uncanny X-Men #1, September 1963.

The Legend: During his travels around the world, in Cairo, he was pickpoceted by a nine year old Ororo Munroe (who would one day become Storm). He followed her but was distracted by Amahl Farouk - The Shadow King, a fellow mutant telepath using his powers for evil. The two battled on the "astral plane. Farouk was defeated, and Xavier decided to be an adventurer, to seek out mutants.
In Isreal he met Eric Magnus who later on became the evil Magneto.
He went to Tibet, where the people were being treated harshly by an evil ruler no one had ever seen. Charles lead a revolt, rallied the people and defeated the ruler. This ruler, whose name was Lucifer, was actually an advanced alien scout for his race which would soon invade Earth. Just before being defeated, Lucifer dropped a huge stone on Xavier's legs; crippling him permanently.
Chuck was airlifted to a hospital in India, where he met Amilia Voght, an american nurse. Being the only two americans there, Amy decided to hook up with Xavier and hit on him hard. The two stayed together for a while, neither one realizing the other was a mutant! However, they both found out about each other during an argument over Charles plan to find mutants, which Amy took great offense to being a mutant herself.
Eventually he made his way to London, where he renewed his friendship with Dr.Moira MacTaggert, who was now a renowned geneticist, and they began discussing the idea of founding a school for mutants. At this point, Xavier and Vought moved into Charles father's estate. They ended up having a run-in with Eric, who now called himself Magneto. Charles and Magneto exchanged insults and finaly called off thier friendship with threats of death. That's when Charles made the definite decision to open his school for mutants.
Xavier's first student was the 11-year-old Jean Grey, who had been traumatized when she telepathically experienced the emotions of a dying friend. Xavier helped Jean recover and taught her to use her telekinetic powers.
Professor Xavier aproached FBI agent Fred Duncan, who was assigned to "mutant affairs". The two worked together in finding Scott Summers, a boy with red beams coming out of his eyes who caused a distubance. This boy later became Cyclops - the leader of the X-Men. During this time, Amelia left Charles.
Charles Xavier used his ancestral mansion as his base to train young kids to use their mutant abilities. He officially opened his "School For Gifted Youngsters" at his mansion - a fully certified NY school. Over the following months Xavier assembled his original team of "X-Men:" Cyclops, Iceman, Angel, Beast, and Jean Grey, who took the name Marvel Girl later known as Phoenix.
Much later, Charles Xavier died. But unknown to all except Jean, he had the Changling; Morph assume his form and then die. Xavier went into a Psi-sheilded chamber where he spent several months preparing for the attack of the Z'Noxx; an alien race related to Lucipher. Porfessor X battled the aliens telepathically without a single shot being fired on Earthen soil. He finally succeeded in driving of the attackers.
Years later, when most of his original students were captured by the mutant Krakoa, Xavier recruited a new team of X-Men, including Banshee, Colossus, Nightcrawler, Storm, and Wolverine. In subsequent years he added more members to the X-Men, such as Rogue and Spritewho later went by the name of Shadowcat.
Sometime before the recruitment of Kitty Pryde; Professor X discovered a new love in Lilandra Narmani, sister of D'Ken Narmani, Leader of the Shi'ar Empire. With D'Ken defeated, Proffesor X and Lilandra, dispite the distance of galaxies and their leadership responsibilities, continued a romance that lasted a very long time. However, Professor X faced a great loss soon therafter, when Pheonix (an alien entity which everyone thought was Jean Grey) commited siucide to save the universe from itself, also prompting Cyclops to leave the team.
The alien race called the Brood had secretly implanted an egg within Xavier's body. MacTaggert and the X-Men's spacefaring allies, the Starjammers, saved Xavier by transfering his mind into a newly cloned, somewhat younger body in which he could once again walk. During this time, Professor X thought his team was killed in battle with the Brood so he set up a new team called the New Mutants. In subsequent months Xavier suffered physical injuries and psychic strains that left him on the brink of death. Lilandra and the Starjammers took him into outer space where they used Shi'ar technology to restore him to health. Xavier entrusted the leadership of the New Mutants with Magneto who had somehow become good. Xavier led the X-Men against the Shadow King, only to have his spine broken in battle, leaving him crippled and confined to a wheelchair once more.
When Xavier returned from space, he found that the New Mutants were now calling themselves The X Force . Magneto had once again reverted to his former self so the X Force was being led by Cable. Also, there was a new team formed in England called Excalibur which consisted of Shadowcat, Nightcrawler and Pheonix among others. Both the original and second teams of X-Men reassembled under his leadership, along with new recruits like Gambit and Jubilee. Professor Charles Xavier divided all the X-Men into two groups : The Blue Team with Cyclops, Wolverine, Jubilee, Psylocke, Beast, Gambit and Rogue; and The Gold Team with Storm, Jean, Iceman, Archangel, Colossus, Bishop, Banshee and Forge.
Since the X-Men were all now highly trained adults, Xavier renamed the school in his mansion The Xavier Institute for Higher Learning. He took control of a private school, the Massachusetts Academy, and made it the new School for Gifted Youngsters, where yet another new class of young mutants, Generation X , was taught.
Later, in a fight against Magneto, Xavier used his mental powers to shut down Magneto's mind. In the process Xavier's mind was inadvertently infected by the evil within Magneto's psyche. The result was that the dark sides of Magneto's and Xavier's minds combined and physically manifested themselves as the nearly invincible entity called Onslaught, who usurped Xavier's psionic powers. Onslaught battled all of America's heroes, in the process transporting them to an alternate universe; leaving only X-Men to fight the threat. Before the X-Men destroyed Onslaught the demon took away Xavier's powers. After the incident, Xavier surrendered himself to the authorities. To ensure that Xavier never again spawned a being like Onslaught, Dr. Valerie Cooper of the United States government took him into custody. Although Xavier was willing to serve as a prisoner of the United States government, he was appalled when it turned him over to the custody of Bastion, head of the anti-mutant Operation: Zero Tolerance. At present, Professor Charles Francis Xavier's whereabouts reamin a mystery.

Charles Xavier is a leading authority on genetics, mutation, and psionic powers, considerable expertise in other life sciences, highly talented in devising equipment for utilizing and enhancing psionic powers. Professor X ordinarily possesses vast psionic powers, including telepathy; the ability to induce in others mental illusions, temporary mental or physical paralysis, and loss of specific memories or total amnesia; the projection of "mental bolts" to stun or render a person unconscious; astral projection; and the ability to sense other superhuman mutants within a small radius.

X-Men #1