A shocking MCU theory could provide the perfect origin story for Robert Downey Jr.’s Doctor Doom in Avengers: Doomsday, and it all comes back to one huge storyline from 20th Century Fox’s X-Men franchise. Robert Downey Jr. was confirmed to be returning to the MCU in 2024, set to appear as Victor Von Doom in Avengers: Doomsday and Secret Wars. However, given Downey Jr.’s former career as the MCU’s Tony Stark, a.k.a. Iron Man, his Doctor Doom is expected to be from an alternate reality, which has spurred many origin story theories.

Robert Downey Jr. once again stressed his importance to the MCU’s Phase 6 during a lengthy livestream that announced the first 27 confirmed members of Avengers: Doomsday’s cast. This presentation revealed that Doctor Doom will be opposed by members of the Avengers, the Thunderbolts and the Fantastic Four, but they’ll also be joined by several X-Men members from Fox’s two-decade-long franchise. A new theory suggests that the X-Men’s return could explain Doctor Doom’s own origin story, which could be game-changing for the MCU.

Avengers: Doomsday Will Bring Back Fox’s Classic X-Men Team

Fox’s Classic X-Men Team Hasn’t Been Seen Since 2014

Introduced back in 2000’s X-Men and featured as the focus of 20th Century Fox’s original X-Men trilogy, many members of the classic X-Men team have now been confirmed to be reprising their roles in Avengers: Doomsday. Most notably, Doomsday will mark the return of Patrick Stewart’s Professor X and Ian McKellen’s Magneto, but they’ll also be joined by some exciting and surprising additions. James Marsden, Rebecca Romijn, Alan Cumming, Kelsey Grammer and Channing Tatum have all also been revealed to be coming back, which is incredibly exciting for the MCU.

There are several members of the original X-Men team and other versions of the group from 20th Century Fox’s franchise that we’re still waiting to get confirmed. This includes some Marvel legends such as Halle Berry, Famke Janssen, Shawn Ashmore and even Hugh Jackman and Ryan Reynolds, who recently joined the MCU in 2024’s ᴅᴇᴀᴅpool & Wolverine. These may not be the only X-Men-related characters appearing in Avengers: Doomsday, however, as a new theory suggests Doctor Doom could even be linked to the mutant superhero team.

Tony Stark Warned Of The Dangers Of Messing With Time In Avengers: Endgame

Tony Stark Discovered Time Travel In Avengers: Endgame 4 Years After The X-Men

Back in Avengers: Endgame, Scott Lang’s return from the Quantum Realm kick-started the Avengers planning the Time Heist to collect the Infinity Stones from the MCU’s history and reverse the devastation caused by Thanos in Infinity War. While Lang provided the idea, it was Robert Downey Jr.’s Tony Stark who put his genius to work discovering how to safely travel through time. This came with a warning, however, as Stark suggested that “when you mess with time, it tends to mess back,” but this quote has never actually been explained in the MCU.

As far as we know, Tony Stark had no knowledge of time travel prior to Avengers: Endgame, so he had no way to know that time messes back when it’s messed with. A new theory suggests that this line could explain Robert Downey Jr.’s return to the MCU. Four years before Endgame, 2023’s X-Men learned how to travel through time using Kitty Pryde’s power, and Wolverine’s consciousness was sent back to 1973 to stop the Sentinel war. It’s possible Tony Stark’s quote might have formed a link to X-Men: Days of Future Past’s dramatic storyline.

Doctor Doom Comes From Fox’s Changed X-Men Timeline In Doomsday: MCU Theory Explained

Victor Von Doom Could Have Emerged Because Of The X-Men Meddling In Time

A new theory shared on Instagram suggests that Robert Downey Jr.’s Doctor Doom could have emerged following the X-Men changing the timeline of Fox’s X-Men franchise in Days of Future Past. The 2014 movie saw the timelines of the original trilogy and the prequel series converge, with Wolverine heading back to 1973 and changing history. This altered many huge events in the subsequent years, transforming villains such as Mystique and Magneto into heroes and antiheroes, and even bringing ᴅᴇᴀᴅ heroes, such as Beast, Jean Grey, Cyclops and Storm, back to life.

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Changing the entire world on this scale would have surely caught the attention of some multiversal forces. The Time Variance Authority were apathetic towards Earth-10005 in ᴅᴇᴀᴅpool & Wolverine because of its deterioration, but now it’s been saved, this could change. The theory suggests that Doctor Doom wouldn’t have emerged in Fox’s original timeline, but was created because of Wolverine’s meddling in time, twisting Robert Downey Jr. into a formidable villain instead of one of Marvel’s most powerful and world-renowned heroes.

What Doctor Doom Being Connected To The X-Men Would Mean For The MCU

Doctor Doom Is The Fantastic Four’s Archenemy, But Has Opposed Many Other Heroes

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While Doctor Doom is typically depicted as the archenemy to Marvel Comics’ Fantastic Four, he has faced almost every other hero in the Marvel Universe in the six decades after his debut in 1962’s The Fantastic Four #5, and this includes the X-Men. This means it would make sense for Doctor Doom to be connected to the X-Men in Avengers: Doomsday. Setting his origin story on Earth-10005 would provide the perfect excuse to remove him in lieu of a new Victor Von Doom after Doomsday and Secret Wars​​​​​​​, as this will likely be the case for the X-Men, too.

It will be great to see the classic X-Men team return in Avengers: Doomsday, and connecting Robert Downey Jr.’s Doctor Doom to them will give him more credibility and create an easy backstory for him. There have been concerns that Doctor Doom would be rushed into the MCU, but if he’s from Fox’s X-Men franchise, we’ve already been introduced to his world and gotten to know many of his related characters. This would allow Marvel Studios to quickly and easily fill in some gaps to explain Doctor Doom’s debut in Avengers: Doomsday, and explain the X-Men’s dramatic and highly-anticipated return.

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  Thunderbolts*

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  May 2, 2025
  

  
  
  
  

  
  

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  The Fantastic Four: First Steps

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  Avengers: Doomsday (2026)

  
  
  
  
  

  
  

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  Spider-Man: Brand New Day

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  Avengers: Secret Wars

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  May 7, 2027
  

  
  
  
  

  
  

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