Almost 20 years ago, Robert Downey, Jr. was announced as taking on the role of Tony Stark for Marvel's first self-financed movie, Iron Man. The casting of Downey seemed like a huge risk at the time as the then-troubled actor had made headlines with his drug and alcohol abuse. He made his first comeback movie with Shane Black for Kiss Kiss, Bang Bang, but it was Iron Man that relaunched Downey's career into the mesosphere.

The same year as Iron Man came Tropic Thunder, which earned the actor another Oscar nomination. 15 years later, he was nominated for his third Academy Award for Christopher Nolan's Oppenheimer and is considered the frontrunner. Talking to Stephen Colbert, Nolan had nothing but praise for his star and considers casting Downey as Stark one of the greatest casting decisions in history.

"He has such charisma as Tony Stark," Nolan said. "I think him playing Iron Man is one of the most consequential casting decisions that's ever been made in the history of the movie business. And I wanted to give him the opportunity to lose himself in a part, lose himself in another human being the way that great actors love to."