There’s a lot to be excited about with Avengers: Doomsday: the Russo Brothers are returning, the Multiverse saga is coming to an end, and, most importantly, Robert Downey Jr. is coming back to the MCU. Downey Jr.’s return, this time playing the beloved Marvel Comics villain Doctor Doom, was the big reveal at Marvel Studios’ Hall H panel at last year’s SDCC. Marvel Studios are renowned for their secrecy on big upcoming projects, but Downey Jr.’s new role feels extra secretive. While the actor himself remains tight-lipped about the role, the Russos have spilled some details about the Oscar-winning actor’s preparation to play Doom.
During an interview with ET Online, Joe and Anthony Russo were asked about Robert Downey Jr. preparing to play Doctor Doom in Avengers: Doomsday. “Oh, it’s very intense,” said Joe Russo of the actor’s preparation. “It’s a very intense process.” While Downey Jr. isn’t regarded as a “method actor,” he is known to be very involved with the creative development of his characters, his tenure as Iron Man being the prime example. According to the Russos, Doctor Doom is no different. Joe Russo continued:

“He is so immersed in it. He is so dialed in. He’s writing backstory. Costume ideas. We were on the phone this morning. He just loves really rich, three-dimensional characters. I think he just sees a lot of opportunity here with that character.”

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While Downey Jr. has kept very quiet about playing Doctor Doom since it was announced at last year’s San Diego Comic-Con, he has occasionally teased fans in the build-up to Avengers: Doomsday’s release on May 1, 2026. This Valentine’s Day, Downey Jr. shared a Doctor Doom-inspired Valentine’s Day card on social media with the words “Victor Von Valentine” — in reference to Doctor Doom’s real name, Victor Von Doom.
How Will Robert Downey Jr. Return to the MCU?

20th Century Pictures

As exciting as Robert Downey Jr.’s MCU return is, it also left a lot of fans scratching their heads. How will the Avengers react to seeing a new villain with the exact same face as one of Earth’s most beloved heroes? The Multiverse and infinite timelines have opened multiple explanations as to how Downey Jr. could come back as a different character. The most common theory thrown around online is that Downey Jr. won’t be playing the only version of Victor Von Doom, and that another actor will also play the mainline version of the character in Doomsday.
This theory also coincides with The Fantastic Four (who will make their MCU debut in Fantastic Four: First Steps) also playing a major role in Avengers: Doomsday. It has already been confirmed that First Steps will take place in an alternate, retro-futuristic universe, and the characters are expected to traverse to Earth-616 (the core MCU universe) by the end of the film. Through their multiversal travel, there is the chance that they could bring Doctor Doom with them, kickstarting Avengers: Doomsday. Of course, nothing has been confirmed by Marvel Studios, and this theory can only be proved once First Steps releases in theaters on Jul. 25, 2025.
Source: ET Online