Stan Lee, who dreamed up Spider-Man, Iron Man, the Hulk and a cavalcade of other Marvel Comics superheroes that became mythic figures in pop culture with soaring success at the movie box office, died at the age of 95.

Lee got started in comics in 1939, when he joined Timely Comics as an office assistant. The publisher, founded by Lee's cousin-in-law Martin Goodman, would eventually transform into Marvel Comics in 1961. Lee's work as an editor started 20 years earlier, when he stepped in as Timely's interim editor in 1941. But the work he's best known for happened in the '60s, when he came up with early Marvel Comics heroes like the Fantastic Four. Comics had traditionally been meant for a younger audience, but Lee saw potential in telling stories for an older crowd.