Warning! This article contains spoilers for The Fantastic Four: First Steps.

Thanks to The Fantastic Four: First Steps, I am convinced that Doctor Doom will be Avengers: Doomsday‘s main character. The ending of The Fantastic Four: First Steps did not do much to actively set up Avengers: Doomsday, with the team remaining in their contained universe after defeating Galactus. Fantastic Four: First Steps’ post-credit scene, however, changed this.

The scene mᴀssively teased the 2026 Marvel movie by officially introducing Doom to the MCU multiverse. How exactly Avengers: Doomsday‘s story is going to play out remains to be seen, but The Fantastic Four: First Steps provided a fairly big foundation for some theories to be crafted.

One theory in particular links directly to the film’s post-credit scene and one of The Fantastic Four: First Steps‘ biggest characters. Stemming from this theory, I am more convinced than ever that Doctor Doom will be presented as the lead character of Avengers: Doomsday.

The Fantastic Four: First Steps Teases Doctor Doom’s Avengers: Doomsday Role

Doom’s Multiversal Plan Could Be Linked To A Fantastic Four Character

Firstly, it is worth exploring exactly what happened in The Fantastic Four: First Steps‘ post-credit scene and how this has formed a specific Marvel theory based on the Secret Wars comic books. The scene shows Sue Storm reading to a now four-year-old Franklin Richards before leaving him on the couch to find his favorite book.

Upon returning, Sue sees a figure clad in a green cloak with a metal mask in its left hand kneeling in front of Franklin. Franklin reaches out to touch this person’s face before the scene cuts to black, and the message that The Fantastic Four will return in Avengers: Doomsday flashes on screen. Of course, this figure is Doom himself.

Given that this scene focused on a connection between Doom and Franklin Richards, I have a theory that the latter will be the MCU’s version of the Molecule Man. In the 2015 Secret Wars comic book event, Doom teams up with Doctor Strange and the Molecule Man to stop incursions across the multiverse.

Eventually, Doom realizes he cannot save the multiverse and uses the Molecule Man’s power to create Battleworld, a combination of the last surviving dimensions. Avengers: Secret Wars’ story is likely set to include Battleworld, meaning Avengers: Doomsday will establish how this came to be. After The Fantastic Four: First Steps, I think Franklin has a part to play.

Franklin is a being of insane power in Marvel Comics, even having the ability to create universes. I think the MCU will combine this with the Molecule Man’s Marvel Comics abilities, revealing Franklin as the person Doom enlists to stop the multiversal incursions, explaining the somewhat intimate connection shown in The Fantastic Four: First Steps’ post-credit scene.

Doom Taking Franklin Could Make Him Avengers: Doomsday’s Main Character

Based On His Motivations In The Comic Books

If Doom does take Franklin, as the MCU’s Molecule Man, in an attempt to stop the incursions threatening the multiverse, it would make sense to have him as Avengers: Doomsday‘s main character. In Avengers: Infinity War, the Russo Brothers described Thanos as that film’s main character, as it focused on his plight to save the universe from overcrowding, albeit with undesirable methods.

Doom wanting to stop multiversal incursions is a fairly noble intention, even if kidnapping Franklin and eventually ruling over Battleworld reinforces his villainous aspects. Avengers: Doomsday can focus intently on Doom by giving him the most screentime and outlining his attempts to save the multiverse, allowing him to be the lead of the film.

Marvel Has Already Proven That Doom Being A Lead Character Can Work

As Have The Russo Brothers

Thanks to Avengers: Infinity War, Marvel Studios has already proven that Doom being the lead character of Avengers: Doomsday can work. Thanos received the most screen time in Avengers: Infinity War, and to great effect. This screen time allowed Thanos’ motivations to be undoubtedly clear, all while making him just sympathetic enough to somewhat care about his plight.

In making him the film’s protagonist, though, enough time was also dedicated to making Thanos’ villainy shine through, so that audiences still rooted for The Avengers. If the Russo Brothers repeat this with Doctor Doom in Avengers: Doomsday, it could work just as well as it did in Avengers: Infinity War.

Doom is also even more sympathetic in some ways than Thanos in the comics. If this is depicted well and the balance between reluctant hero and power-hungry villain is struck, Avengers: Doomsday having Doom as its main character could work even better than Avengers: Infinity War‘s depiction of Thanos.

Doctor Doom Being The Main Character Of Avengers: Doomsday Makes RDJ’s Casting Better

Aiding A Somewhat Controversial Casting Choice

Robert Downey Jr.’s casting as Doctor Doom in Avengers: Doomsday has been controversial for several reasons. Many think that Marvel is just banking on the nostalgia of Iron Man with this casting choice, while others wanted someone of Romani descent to portray Doom due to his comic book heritage. Both are certainly valid complaints, but this main character theory could alleviate other worries.

After all, even those who have these complaints acknowledge that, purely from an acting perspective, Robert Downey Jr. is talented enough to portray a complex character like Doom. If Doom becomes Avengers: Doomsday‘s main character, this acting talent will be on display, front and center. RDJ’s talents would be wasted on a smaller villain role, so a bigger one makes sense.

RDJ should be on screen as much as possible, especially after the big deal Marvel Studios made over his casting. If this theory from The Fantastic Four: First Steps comes true and Doom spends the story of Avengers: Doomsday trying to stop multiversal incursions, he would be the film’s main character and give RDJ time to shine.