The X-Men are a team of mutant superheroes in the Marvel Universe. They were created by writer Stan Lee and artist Jack Kirby, and first appeared in The X-Men #1 (September 1963). The basic concept of the X-Men is that 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.[1] Xavier recruited Cyclops, Iceman, Angel, Beast, and Marvel Girl, calling them "X-Men" because they possess special powers due to their possession of the "X-gene," a gene which normal humans lack and which gives mutants their abilities. Early on, however, the "X" in X-Men stood for "extra" power which normal humans lacked. It was also alluded to that mutations occurred as a result of radiation exposure.

The first issue also introduced the team's archenemy, Magneto, who would continue to battle the X-Men for decades throughout the comic's history, both on his own and with his Brotherhood of Mutants (introduced in issue #4). The X-Men universe also includes such notable heroes as Wolverine, Storm, Colossus, Nightcrawler, Rogue, and Shadowcat. Besides the Brotherhood of Mutants, other villains that the X-Men have fought include the Sentinels, Apocalypse, Mister Sinister, the Marauders, the Hellfire Club, and the Purifiers.

The X-Men comics have been adapted into other media, including animated television series, video games, and a commercially successful series of films.