The X-Men first appeared in 1963, in a self-titled comic book written by Stan Lee and drawn by Jack Kirby. It featured the telepathic Professor Xavier and his team of super-powered pupils: mutants who were born with their powers, rather than receiving them some other way.
The X-Men comic was cancelled after issue #66, but revived in 1975 with "Giant Size X-Men #1." It featured a new team of international mutants under Professor X, including the Canadian Wolverine, the Russian Colossus and the German Nightcrawler.
Writer Chris Claremont presided over a perceived Golden Age of the X-Men when he wrote for the comics in the 1980s.
New titles under the X-Men banner, such as "X-Factor" and "The New Mutants," began appearing in the late 1980s, and exploded in the 1990s. Claremont left the line around that time, as artists like Jim Lee were given increasingly preferential treatment.
The arrival of the successful X-Men movies, starting in 2000, helped keep the line reinvigorated, as team members were shuffled between books, and new titles continued to be introduced.