A brutal MCU fan theory predicts Avengers: Doomsday will bring back Josh Brolin’s Thanos only for Robert Downey Jr.’s Doctor Doom to kill him in the opening scene. Avengers: Doomsday‘s cast announcement confirmed the return of over two dozen Marvel characters, including the Thunderbolts, the Avengers, and Fox’s multiversal X-Men. Other MCU characters may also return, either in major roles that haven’t been announced yet or in cameo appearances that make the most out of Avengers: Doomsday‘s multiversal premise. Some of these supporting characters may include TVA agents, minor MCU heroes, and ᴀssorted mutants from different X-Men timelines.

The concept of the multiverse opens up countless possibilities for Avengers: Doomsday and Avengers: Secret Wars. Avengers: Infinity War and Avengers: Endgame exceeded all expectations regarding cameos, going as far as featuring cameos such as Red Skull, Howard Stark and Jarvis, Frigga, the Ancient One, Alexander Pierce, Crossbones, and Harley Keener. Avengers: Doomsday and Avengers: Secret Wars can up the ante with new cameos by characters from all over the Marvel multiverse. Aside from characters from Fox’s multiple X-Men timelines, Fantastic Four universes, and possibly Sony’s Spider-Man universes, Phase 6’s crossover movies could introduce new variants of established MCU characters.

Doctor Doom Kills Thanos In Marvel Comics’ 2015 Secret Wars

One Of Doctor Doom’s Greatest Feats Of Power Is Killing Thanos With His Bare Hands

The MCU’s Avengers: Doomsday and Avengers: Secret Wars will likely draw a lot of inspiration from Marvel Comics’ several Secret Wars storylines, including 2015’s highly popular Secret Wars. Prior to this comic book run, Thanos joins forces with villains like Terrax, Maximus, Proxima Midnight, and Namor to destroy universes that are on course to collide with Earth-616. Betrayed by Namor, Thanos and the rest of his team — the Cabal — meet the Ultimate Universe Reed Richards, better known as “The Maker”, and survive Earth-616’s collision with Earth-1610, which leads to the creation of Battleworld and the rise of God Emperor Doom.

God Emperor Doom’s right-hand man, Doctor Strange, sends Thanos to a Battleworld realm inhabited by zombie versions of Marvel characters. Thanos survives the zombies’ attack and escapes, helps create an insurrection against God Emperor Doom’s reign, and decides to confront Doom all by himself. Unimpressed, Doom acknowledges the fact that Thanos isn’t wielding the Infinity Stones in his gauntlet, ignores Thanos’ threats, and punches a hole through his chest. God Emperor Doom then mocks Thanos as he rips the Mad тιтan’s spine from his body. While Thanos eventually resurrects, his Secret Wars death continues to be his most humiliating defeat.

Avengers: Doomsday Has The Chance To Replicate Secret Wars’ Most Brutal Doctor Doom Moment

Thanos’ Death Could Be Doctor Doom’s Best Way To Show Off His Power

Although Avengers: Doomsday and Avengers: Secret Wars are very likely to be based on Marvel Comics’ Time Runs Out and Secret Wars storylines, the MCU won’t adapt the comic books panel-for-panel, as the Multiverse Saga would have needed to follow a significantly different story beforehand. Nevertheless, Marvel Studios could easily adapt God Emperor Doom’s most brutal moment from 2015’s Secret Wars by opening Avengers: Doomsday with a powerful variant who meets his end at the hands of Robert Downey Jr.’s Doctor Doom in an alternate timeline. This timeline could be Doctor Doom’s original universe or a distant reality he invades.

The on-screen death of a live-action Thanos variant played by Josh Brolin would be an appropriate cameo for a movie the scope of Avengers: Doomsday. Avengers: Doomsday might also be one of the few places where Doctor Doom’s most brutal feats of power could fit, as the Multiverse Saga’s conclusion might take with it the possibility of seeing a live-action Thanos on the big screen again. And while Doctor Doom’s murder of Thanos could also take place in Avengers: Secret Wars, Avengers: Doomsday‘s opening scene could be the best moment to establish the true extent of Doom’s power and ambition.

Thanos’ Death In Avengers: Doomsday Would Repeat A Great Infinity War Trick

Avengers: Doomsday’s Opening Scene Has The Chance To Flip Loki’s Infinity War Death

Avengers: Infinity War‘s opening sequence saw Thanos decimate the Asgardian survivors fleeing Asgard’s destruction. Thanos’ attack claimed the lives of Heimdall and countless other Asgardians. Most notably, Loki failed to trick Thanos and hide the Tesseract, leading Thanos to break Loki’s neck and bring a definitive end to the original God of Mischief’s life. Loki’s death in Avengers: Infinity War follows a very similar structure to Thanos’ death in 2015’s Secret Wars, including the victim’s threatening final words and the murderer’s brutal killing method. In Avengers: Doomsday, Doctor Doom could give an alternate-universe Thanos a taste of his own medicine.

Similarly to how Avengers: Infinity War brought back The Avengers‘ main villain just to kill him off during the opening sequence, Avengers: Doomsday could bring back Avengers: Infinity War‘s main villain and kill him off during its opening scene in order to prove just how powerful Doctor Doom is in comparison. This is exactly what Marvel Comics’ 2015 Secret Wars did with Thanos’ brutal death, and it could have an even clearer effect on the big screen considering that Thanos was the Infinity Saga’s overarching villain and the one who led many key MCU characters to their death, including Loki.

Marvel Has Already Proved Thanos’ Best Future Is Propping Up Other Villains

Thanos Might Only Return In One-Off Appearances That Kill Him Off Immediately

Ever since Iron Man performed the third snap to kill Thanos and his forces in Avengers: Endgame, the MCU has brought Thanos back multiple times just to kill him off immediately afterward. Ronan, Killmonger, Infinity Ultron, and an alternate-universe horde of zombies have been some of the characters who killed alternate Thanos variants in What If…?, and Earth-838’s Illuminati apparently stabbed the Mad тιтan with his own sword on тιтan years before the events of Doctor Strange in the Multiverse of Madness. Robert Downey Jr.’s Doctor Doom could join the growing list of Thanos killers in Avengers: Doomsday‘s opening scene.

While Thanos is a villain with enough potential for multiple new appearances, the only way Marvel Studios might be able to bring the Mad тιтan back without undoing Avengers: Endgame might be by killing off his multiversal variants. If Thanos came back as a genuine threat, the dramatic weight of the original Thanos’ defeat in Avengers: Endgame could be diminished, as the original variant would no longer seem unique. Killing off too many Thanos variants also risks turning the villain into a joke character. Therefore, Marvel could retire the Mad тιтan for good with a final send-off in Avengers: Doomsday.

X Alternate-universe Thanos variants made cameos dying in What If…? and Doctor Strange in the Multiverse of Madness. This might be the only way to bring back Thanos effectively, as depicting him as an actual threat would undo Avengers: Endgame’s ending.

Upcoming MCU Movies

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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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  July 25, 2025
  

  
  
  
  

  
  

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  Avengers: Doomsday (2026)

  
  
  
  
  

  
  

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  Spider-Man: Brand New Day

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  July 31, 2026
  

  
  
  
  

  
  

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  Avengers: Secret Wars

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  May 7, 2027
  

  
  
  
  

  
  

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