Image Credit: Getty Images The Avengers have assembled! Avengers: Doomsday has its full cast, and Marvel fans are dying to see the film come to life on the big screen on December 18, 2026, since its release date was pushed back. The hype really kicked off when Robert Downey Jr. unmasked himself to be playing Doctor Doom at the 2024 San Diego Comic Con, but the Iron Man actor isn't the only major star in the cast. Several MCU veterans and newcomers will accompany Robert on screen.