Avengers: Doomsday Trailer Sparks Theories About 2 Doctor Dooms as Fans Hope for a Surprise Cameo from Cillian Murphy

The new Avengers: Doomsday trailer is here, and some fans believe it has a few clues that suggest the film is hiding two Doctor Dooms – and maybe even a cameo from Cillian Murphy.

Warning! Potential spoilers for Avengers: Doomsday follow.

Marvel Studios has seemingly been pretty forthcoming when it comes to the cast for this year's new Marvel Cinematic Universe (MCU) movie. Of the long lineup of A-listers on the call sheet are faces from the X-Men, Fantastic Four, and more, but the casting choice that has remained controversial among fans since its announcement is Iron Man actor Robert Downey Jr. as Victor von Doom.

The few Avengers: Doomsday clips we've seen thus far have revealed the hero-turned-villain star's in-costume look – or have they? That's the question fans have been asking since the team-up film's new trailer arrived as part of D23 2026. With tens of millions of viewers in just a few days, it's clear the video has something to offer ahead of the full premiere in December, but some believe it's hiding a few clues about Doctor Doom duplicates, too.

"All of you have lived stolen lives," he can be heard saying in between shots of a screaming Reed Richards played by Pedro Pascal. "But now you must give them back."

Where past sneak peeks for the movie haven't dived too far down the Victor von Doom rabbit hole, the D23 trailer is really more about him than any of Earth's Mightiest Heroes. It starts with Vanessa Kirby's Sue Storm talking about the Latverian leader as someone who "used to be kind" and "caring" before we then see him toss Thor like an ant and raise an army of sentinels. Although he certainly seems to present an Avengers-level threat that could rival Thanos, the conversation surrounding his identity lies in the details.

A few close-ups of the magic-powered villain's eyes are all we really get when it comes to glimpses of what's behind his metal mask, but that's all fans online needed to stir up conversation. You see, this character has bluish-green eyes, while Downey Jr.'s are brown. This Doctor Doom also has a small mole next to one of his eyes, where the actor believed to be playing him does not.

"One looks blue. The other video looks brown," one fan speculated after the trailer was released. "Is there more than one Doom?"

"I think there will be two Dooms," another said. "The real Doom, and a Tony variant."

The idea, then, is that the Doom we've seen here is a different one from the Doom Downey Jr. is playing. If these are truly our first signs that Avengers: Doomsday features more than one Doctor Doom, then the next logical question is 'Who is playing the other one?' Many online believe Murphy, who is best known for starring in movies like Oppenheimer and 28 Years Later, makes the most sense. He was a popular fancast pick as Marvel put the new Avengers movie together behind the scenes early on. He also happens to have much lighter eyes.

Many believe Downey Jr. could be playing a good-guy version of the character, leaving the evil one to be played by Murphy or even someone else. Other theories rattling around social media feeds have revolved around a surprise return for Michael Fassbender's Magneto, an alternate Reed Richards, or, if Marvel is feeling really daring, Chris Evans' Steve Rogers.

This is all proof that a mystery actor is playing Doom and not the former Iron Man star, right?! Well, no. As others have pointed out, that mole might seem a bit strange, but some combination of movie magic and special contact lenses could easily explain away these discrepancies. That's done little to stop the theories from spinning on.

"This is literally just RDJ with colored contacts y’all overthinking it lol," one fan argued.

"lmao they are not paying RDJ multi millions to play a fake Doom," another teased.

"Why not? They paid Ben Kingsley millions to play a fake Mandarin," another user replied.

Meanwhile, the appearance of a second, new costume for Victor von Doom that popped up at D23 has helped fuel the Avengers: Doomsday theory fire through the weekend. Some blink-and-you'll-miss-it moments in the trailer also show what appears to be a smoother, less angry mask design and a more simplistic suit. It does seem odd that the big bad guy would care enough about his fashion to have slightly different outfits for specific occasions.

Even then, though, we already knew Doom would be switching his clothes. The costume and mask featured in most promotional material is already quite different from what we saw at the end of last year's The Fantastic Four: First Steps. The reasoning behind the change is unclear, with some suspecting one might be for fighting off superheroes, while the other is used when Doom wants to favor more peaceful methods.

Regardless of whichever side of the theory fence you fall on, it's hard to blame the fans of a cinematic movie universe that has reveled in multiversal shenanigans for the last seven years. Character variants have, quite famously, occupied the same screen more than a few times. If Spider-Man did it, Doctor Doom can too, right?

It's certainly possible, but there is much, much more MCU to watch before we get all of the answers. Avengers: Doomsday will pull back its green curtain to clear up many of its mysteries when it premieres December 18, 2026, but it's far from the end. The film will then lead directly into Avengers: Secret Wars, which won't arrive until another year later, come December 17, 2027.

So, will there be two Doctor Dooms? Is Downey Jr.'s character the movie's villain or its hero? Will Iron Man come back from the dead? We'll have to wait to find out. Until then, you can see how Marvel announced the first batch of cast members for its new X-Men movie. You can also check out the new trailer for the upcoming MCU TV show, VisionQuest. Finally, be sure to catch up on all of the biggest D23 news from the Disney Entertainment Showcase right here.

Photo by Jacob King/PA Images via Getty Images.

Michael Cripe is a freelance writer with IGN. He's best known for his work at sites like The Pitch, The Escapist, and OnlySP. Be sure to give him a follow on Bluesky (@mikecripe.bsky.social) and Twitter (@MikeCripe).