"At the time, DC Comics had a book called The Justice League, about a group of superheroes, that was selling very well. So in 1961 we did The Fantastic Four. I tried to make the characters different in the sense that they had real emotions and problems. And it caught on. After that, Martin [Goodman, who founded Timely Comics] asked me to come up with some other superheroes. That's when I did the X-Men and The Hulk. And we stopped being a company that imitated."