Gage Skidmore · CC BY-SA 3.0

Stan Lee spent two decades as Marvel's primary creative engine, co-creating Spider-Man, the X-Men, the Fantastic Four, Iron Man, Thor, and the Hulk with artists Jack Kirby and Steve Ditko in a burst of output through the 1960s that pushed superhero comics toward more naturalistic, flawed characters. In the 1970s he challenged the industry's self-censorship board, the Comics Code Authority, and helped force it to loosen its restrictions. After retiring from Marvel's day-to-day operations, he became the company's public face, making cameo appearances across its films.