Only three major heroes are up to the task of defeating Robert Downey Jr.'s Doctor Doom in Avengers: Doomsday. Defeating the Infinity Saga's big bad Thanos required all six Infinity Stones and the tragic sacrifice of Robert Downey Jr.'s Iron Man. Now that the MCU's Founding Father is back for Doomsday and Secret Wars as Doctor Doom, who is arguably even more powerful than Thanos with his unique blend of magic and technology, very few will be up to the task of beating him.
Most fans seem to agree that Doomsday will end on a similar note to Infinity War, with Doctor Doom victorious and more powerful than ever going into Secret Wars. The leading theory has Doom gaining control over the Multiverse from Loki, who is currently holding all of its branches together, to create Battleworld from the remnants of what is left after Incursions ravage almost all of reality.
If that theory proves true, the surviving heroes will have to band together on Battleworld to overthrow God Emperor Doom and restore the Multiverse in December 2027's Avengers: Secret Wars. Even then, there are only three heroes who currently stand a chance at defeating Doom once and for all.
3 MCU Heroes Most Likely to Defeat RDJ's Doctor Doom
Reed Richards
The heated rivalry between Reed Richards and Doctor Doom has been at the center of many Marvel Comics storylines, including 2015's Secret Wars, which makes Pedro Pascal's Mr. Fantastic an obvious candidate to defeat Doom.
Many will be aware that Secret Wars sees Doctor Doom channels the power of the nigh-omnipotent Beyonders with the help of Molecule Man to create Battleworld. In the final confrontation between Richards and Doom, the villain concedes that the Fantastic Four hero would have done a better job with that limitless power, leading Molecule Man to transfer it to him so he could rebirth the Multiverse.
Of course, Doom finally admitting defeat to Richards wouldn't have quite the same impact in the MCU, given that they will only meet for the first time on-screen in Doomsday. But that's not to say they don't have many years of off-screen history on Earth-828 that could be established enough in two Avengers movies for Doom's confession to still carry some weight and mark a satisfying ending.
Steve Rogers
Marvel Studios is ripping Chris Evans' Steve Rogers out of retirement for Avengers: Doomsday, connecting directly to his Endgame happy ending. As one of the MCU's biggest changes to Doctor Doom, it seems his biggest grudge is with Rogers, whose time traveling actions led to the villain's family's deaths.
Much like Captain America: Civil War, the MCU's next Avengers blockbusters seems to be putting Evans and Robert Downey Jr. at odds. There's no doubt that will frustrate many who would rather see the classic rivalry between Doctor Doom and Reed Richards, but it makes Rogers a strong contender to take him out.
Such a moment could see the former Captain America accept the consequences of his actions, making a sacrificial play akin to Iron Man in Endgame. That said, pulling Rogers out of retirement after seven years just to defeat the big bad and possibly die in the process could feel somewhat narratively cheap.
Loki
Tom Hiddleston's Loki has had one of the MCU's strongest character arcs over the last 15 years. He has also been a cornerstone of the Multiverse Saga thanks to his two-season Disney+ series that redeemed the God of Mischief, birthed the MCU's Multiverse, and saw Loki become its all-powerful savior, the God of Stories.
In 2015's Secret Wars, Doom got the infinite power to create Battleworld forcefully from the Beyonders, and the God of Stories will reportedly assume that role in Avengers 5. If Loki is the source of Doom's new powers, he could be a strong candidate to defeat him, marking a perfect end to his MCU storyline.
By the time the Multiverse Saga ends, Hiddleston will have been in the MCU for over 16 years, due to the principle that Loki never dies. There may not be a more fitting a death for him than making the sacrifice play to defeat Doom, completing his redemption and taking the MCU full circle, given that the God of Mischief was the first foe for Earth's Mightiest Heroes back in 2012's The Avengers.
