The X-Men (comic book series)
The X-Men is a Marvel comic book series begun in 1963. It is essentially a superhero team story; the superheroes are all mutants.
The series was groundbreaking in a number of ways, and the concept of "mutants" offered Marvel an opportunity to metaphorically treat discrimination -- first racism, and later homophobia.
The series also featured the first major Black female superhero, Ororo Munro (Storm).