X-Men is a popular comic book series created by Stan Lee and Jack Kirby that first appeared in 1963. The story revolves around a group of superheroes known as mutants, who possess extraordinary abilities due to a genetic mutation. They often face discrimination and conflict with humans who fear their powers, leading to themes of acceptance and diversity. The main characters include Professor X, the leader who promotes peaceful coexistence, and Magneto, who believes in mutant superiority. The team, known as the X-Men, fights to protect both mutants and humans from various threats, including villains like Mystique and Apocalypse.