The X-Men are a fictional Marvel Comics superhero team. Created by Stan Lee and Jack Kirby, they debuted in The X-Men #1, published in September 1963.

The central theme of the series is that the X-Men are superheroes who acquired their powers from birth rather than through incident or design (similar to the Fantastic Four, Spider-Man, and Captain America). Most of them are initially teenagers who learn how to use their powers at a special school run by Professor Charles Xavier (though the "school" takes the feel of a military academy given that the X-Men's powers are used mainly for conflict and are often sent into battle).

The X-Men are fictitious mutants who, as a result of a sudden leap in evolution, are born with latent superhuman abilities that generally manifest themselves at puberty. In the stories, many ordinary humans harbor an intense fear or distrust of mutants (often referred to as Homo superior), who are regarded by a number of scientists as the next step in human evolution. They are thus widely viewed as a threat to human civilizations; mutants who use their powers for criminal ends exacerbate the tensions. The X-Men were formed by the benevolent Professor Charles Xavier, (a.k.a. Professor X), a wealthy mutant who founded an academy to train young mutants to protect themselves and the world from Magneto, the Brotherhood of Mutants and other mutant threats.

The X-Men comic book series was one of comicdom's earliest and most influential trendsetters in adopting a multicultural central cast; during the 1970s, the roster was diversified, adding characters from Canada, Germany, Ireland, Japan, Kenya, and the Soviet Union. Characters representing many other ethnicities and cultural backgrounds have subsequently been added. The stories themselves have often included themes relating to the status of minorities, including assimilation, tolerance, and beliefs regarding a "superior race".

The X-Men series has been adapted into films and television shows. The television shows have included one of the most successful weekend morning programs, X-Men: The Animated Series, and the hit Kids WB! animated series Category: X-Men: Evolution - . In 2000, the X-Men movie directed by Bryan Singer was released and featured Patrick Stewart as Professor Charles Xavier, James Marsden as Scott Summers (Cyclops), Halle Berry as Ororo Munroe (Storm), Hugh Jackman as Logan (Wolverine), Famke Janssen as Jean Grey (No codename in the films), and Anna Paquin as Marie (Rogue). Its sequel, X2: X-Men United, was released in 2003, again directed by Singer. A third X-Men movie, Category: X-Men: The Last Stand - , directed by Brett Ratner, was released May 26, 2006. By 2008, two more films were in development, one featuring the origin of Wolverine and the other featuring the origins of Magneto.