Robert Downey Jr. almost played this Marvel villain before becoming Iron Man

Before Robert Downey Jr. became synonymous with Tony Stark, the actor auditioned for the villainous role of Doctor Doom in the 2005 Fantastic Four film. This revelation was made by Jon Favreau , director and co-star of the first Iron Man movie, during a 15th-anniversary retrospective to Vanity Fair.

Favreau recalled that Marvel executives were already familiar with Downey Jr. due to his previous audition for Doctor Doom, a role that ultimately went to Julian McMahon. However, Favreau recognized Downey Jr.'s "spark" and advocated for him to be cast as Iron Man, a decision that proved pivotal to the MCU's success.

Kevin Feige, the head of Marvel Studios, credited Favreau and Downey Jr.'s collaboration as the foundation for the MCU's unique tone. He even acknowledged that without Downey Jr.'s portrayal of Iron Man, Marvel Studios might not exist today.

Although Downey Jr. didn't become Doctor Doom, he went on to share the screen with Chris Evans, who played the Human Torch in Fantastic Four before taking on the role of Captain America in the MCU.

Despite his iconic run as Iron Man, Downey Jr. bid farewell to the character in Avengers: Endgame. While fans may hope for his return, Kevin Feige has confirmed that there are no plans to undo Tony Stark's sacrifice.