Robert Downey Jr. is set to return to the Marvel Cinematic Universe as Doctor Doom in the upcoming film "Avengers: Doomsday," directed by Joe and Anthony Russo. Downey has been heavily involved in developing the character, writing backstory and costume ideas. His return as a villain has surprised fans and former cast members, with Jeremy Renner and Benedict Cumberbatch expressing excitement and surprise at the news. "Avengers: Doomsday" is scheduled for release on May 1, 2026, with Downey's return generating significant buzz among Marvel enthusiasts.