TMDb/Avengers: Doomsday Movie Robert Downey Jr. returns to the MCU, not as Iron Man, but as the villainous Doctor Doom in Avengers: Doomsday. A shocking twist for the Multiverse Saga. April 21, 2026 AceShowbiz - In a surprising twist for the Marvel Cinematic Universe, Robert Downey Jr. returns to the franchise not as the beloved Tony Stark but as the menacing Doctor Doom in the upcoming Avengers: Doomsday.