X-Men is an American comic strip team consisting of a rotating ensemble cast of mutants born with superhuman powers. Created in 1963 by writer Stan Lee and artist Jack Kirby, the team became one of Marvel Comics’ most successful properties. The original version of the X-Men was a group of teenagers (never exclusively male, despite the name) who attended Xavier’s School for Gifted Youngsters. By all appearances, the school was nothing more than an elite college preparatory academy in Westchester county, New York. In reality, it served as the training facility and headquarters of the foremost mutant superhero team in the Marvel Universe.

Source: Encyclopedia Britannica