A new MCU theory suggests that Marvel Studios’ upcoming Thunderbolts* could introduce Doctor Doom’s greatest weapon ahead of his Avengers: Doomsday debut. Scheduled to release as the final movie in the MCU’s Phase 5, Thunderbolts* will bring together a new team of superpowered antiheroes and reformed villains to battle one of Marvel’s strongest new characters. Both a hero and a villain, Lewis Pullman’s “Bob” will pose a significant threat to the MCU in Thunderbolts*, and this can continue in Phase 6 thanks to Pullman’s return in Avengers: Doomsday.
Trailers for Thunderbolts* have proven just how dangerous Lewis Pullman’s Sentry, or at least his villainous half, will be in the upcoming 2025 movie. The Sentry is one of Marvel Comics’ most powerful characters, which will make him a formidable adversary to the Thunderbolts team, comprising Yelena Belova, Red Guardian, Bucky Barnes, Ghost, Taskmaster and US Agent. The Sentry’s power could also make him a hot commodity in other upcoming MCU projects, however, namely Avengers: Doomsday, as a new theory suggests he could be harnessed by Robert Downey Jr.’s Doctor Doom.
The Thunderbolts Defeat Sentry, But At A Cost: MCU Theory Explained
Lewis Pullman Will Debut As Robert Reynolds’ Sentry In Thunderbolts*
It’s been all but confirmed that Robert Reynolds will be transformed into the super-soldier Sentry by Valentina Allegra de Fontaine in Thunderbolts*, though his evolution into the villainous and dark Void was surely not part of Val’s plan. This will explain the Thunderbolts’ formation, as the Void may seek vengeance on Valentina, and perhaps use all of New York City as leverage. We’ve seen the Void violently and shockingly turning innocent New Yorkers into shadows in Thunderbolts*’ trailers, which seems to imply that there will be countless casualties and a huge cost in the Phase 5 movie.
Since Lewis Pullman has been confirmed to be returning to the MCU in Avengers: Doomsday, it seems likely that the Thunderbolts will work out some clever way to revert the Void back to the Sentry. However, Robert Reynolds will then be faced with the consequences of the actions of his dark alter ego, as the Void may cause hundreds of deaths. The gravity of this realization could urge Reynolds to isolate himself – just as we saw the Scarlet Witch do after WandaVision – which sets up a fantastic theory that explains the Sentry’s role in the MCU’s Phase 6.
Sentryโs Isolation Could Lead Him Right Into The Arms Of RDJโs Doctor Doom
Robert Downey Jr.’s Doctor Doom Could Harness The Sentry’s Power In Avengers: Doomsday
The idea that the Sentry could end Thunderbolts* in isolation sets up a new theory posed by Reddit user CottonBUdy12, which posits that Doctor Doom could manipulate Robert Reynolds in an effort to harness his power. Robert Downey Jr. was confirmed to be cast as Doctor Doom at 2024’s SDCC, but since he will have had no prior set-up before Avengers: Doomsday, he needs to make a strong first impression. Getting the extremely-powerful Sentry under his control and aiming him at the MCU’s heroes as a weapon would be a fantastic way to make this happen.
In Marvel Comics, the Sentry is said to have the power of a million exploding suns, making him one of the strongest super-soldiers ever to exist. This could also be the case in the live-action MCU, which would make Robert Reynolds someone who perhaps many villains would hope to get their hands on, whether to steal his power or to use him. Billed to be the Multiverse Saga’s new primary antagonist, it seems that Doctor Doom may be the one to manipulate the Sentry, and Thunderbolts* may prove this will pose a significant threat to the Avengers.
Doctor Doom Using Sentry In Avengers: Doomsday Would Be Great For Secret Wars
The Sentry’s Avengers: Doomsday Return Could Explain The MCU’s Secret Wars Storyline
The Russo brothers have routinely spoken about their love for Marvel Comics’ Secret Wars storylines, and have revealed that both the 1984 and 2015 events will inspire the MCU’s Doomsday and Secret Wars. This suggests that the Russos will adapt Doctor Doom’s storyline as “God Emperor Doom” on Battleworld, and this story could be set up by Doom taking control of the Sentry’s power. Having Robert Reynolds kill a huge number of the MCU’s heroes could cause the incursion event that forces Doom to create Battleworld, providing a strong explanation for this outlandish event.

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The newest trailer for Thunderbolts* saw Valentina Allegra de Fontaine reveal that the Sentry is “stronger than all of the Avengers rolled into one.” This seems to imply that a battle between the Avengers and the Sentry – or perhaps the Void – will end with Earth’s Mightiest Heroes meeting their bitter ends. This kind of cataclysmic event would surely cause an incursion, so Thunderbolts* could tear down the Sentry enough to perfectly lay the foundations for Doctor Doom’s grand plans in Avengers: Doomsday and Secret Wars.

Thunderbolts*
- Release Date
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May 2, 2025
- Director
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Jake Schreier
- Writers
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Lee Sung-jin, Eric Pearson, Joanna Calo