
Jon Favreau has confirmed that Robert Downey Jr. almost played a totally different Marvel role. The actor debuted as Iron Man in 2008, and played the hero all the way up to 2019's Avengers: Endgame.
In the book Marvel Studios: The Making of the Marvel Cinematic Universe by Tara Bennett and Paul Terry, released in 2021, Favreau mentioned that Downey had a meeting with Marvel about the possibility of playing Doctor Doom (H/T CBR.com).