The X-Men are a superhero team in the Marvel Comics Universe. They were created by writer Stan Lee and artist Jack Kirby, and first appeared in The X-Men #1 (September 1963). Under a cloud of increasing anti-mutant sentiment, Professor Xavier created a haven at his Westchester mansion to train young mutants to use their powers for the benefit of humanity, and to prove mutants can be heroes. Xavier recruited Cyclops, Iceman, Angel, Beast and Jean Grey, calling them "X-Men" because they possess special powers due to their possession of the "X-Gene", a gene normal humans lack but which gives Mutants their abilities. Early on, however, the "X" in X-Men stood for "extra" power which normal humans lacked. It was alluded to that the mutations were incurred as a result of radiation exposure. All five original X-Men, including Professor Xavier were stated to be the children of parents who worked on atomic weapons for the United States military.
Early issues introduced the team's arch enemy, Magneto and hisBrotherhood of Mutants, who would continue to battle the X-Men for decades throughout the comic's history. The X-Men comics have been adapted into other media, including animated television series, video games, and a successful series of films.