In 2024, it was announced that Doctor Doom will be played in the movie – and its 2027 follow-up Avengers: Secret Wars – by Robert Downey Jr, who previously portrayed Iron Man in the Marvel Cinematic Universe. The "Nobody 2" actress got an Oscar nomination for her role in the classic Martin Scorsese movie, but it wasn't easy to film.

It speaks to how stacked Avengers: Doomsday's cast currently is that Cyclops actor James Marsden returning to his iconic X-Men role for the first time in over a decade has barely been a topic of conversation ahead of the MCU crossover event.

James Marsden is opening up about coming back to the big screen as Cyclops. In a recent interview with Vanity Fair, Marsden spoke about how he feels to reprise his role as comic book character Cyclops in the upcoming film, Avengers: Doomsday.