Forget Doctor Doom: Avengers Doomsday Theory Names Captain America the Real Villain
Everyone expects Robert Downey Jr.’s Doctor Doom to be the big bad of Avengers: Doomsday, but a viral theory flips the script — Captain America may have triggered the Earth-616 incursion that brings Doom crashing in.
Here is a twist I did not have on my bingo card: the big bad of Avengers: Doomsday is Doctor Doom — reportedly played by Robert Downey Jr. — but a new fan theory puts the blame for the whole mess on Captain America. Not joking. And based on what insiders say Marvel is about to show in the teasers, it might actually track.
The theory: Steve broke the multiverse
Instagram user @cinemawithdylan lays it out like this: when Chris Evans' Steve Rogers hopped back in time to live out his life with Peggy Carter, that choice splintered the timeline hard enough to trigger an Incursion — the kind of reality-colliding event that yanks Doctor Doom into the MCU's main Earth-616. If that is the setup, the biggest Multiversal threat in Doomsday essentially kicks off because Steve wanted a dance. Messy, but clean as a narrative inciting incident.
Why people think Chris Evans is actually back
Evans has publicly said he was content leaving Cap in the rearview. That was then. Now, multiple reports tied to upcoming marketing say he shows up in Avengers: Doomsday. Industry watcher @MyTimeToShineH claims Marvel has four short teasers lined up before release — not full trailers, but quick scenes that spotlight different characters — and one of them features Steve back on his motorcycle. They also say the rollout order changed late in the game and the Doom-focused piece was supposed to go first.
"They switched the order. Doom was supposed to go first... The four 'trailers' aren't really trailers, they're four short scenes, each focusing on a different character. The one with Steve..." — @MyTimeToShineH, Dec 15, 2025
With RDJ and Chris Hemsworth already circling back, it makes sense Marvel would lean into legacy faces for what amounts to a giant endgame-style showdown.
How this lines up with Secret Wars
If you read the 2015 Secret Wars run, the roadmap sounds familiar. The Multiverse collapses under a wave of Incursions. Doom taps into the Beyonders' power to stop the bleeding, then stitches a patchwork reality called Battleworld where he is in charge. He needs a cosmic battery to keep it standing — enter Franklin Richards, whose god-tier abilities become essential. (That tracks with the end-credits sting in The Fantastic Four: First Steps, which teases Franklin.)
Eventually it all narrows to a fight for the future between Doom and Mr. Fantastic, with the Avengers and basically every other Marvel hero in the mix to reboot reality. If Steve accidentally starts the Incursion that drags Doom into Earth-616, that is your runway into Doomsday and the next Secret Wars movie — and a neat way to thread legacy characters straight through the center of it.
What Doomsday looks like right now
- Directors: The Russo Brothers
- Main antagonist: Doctor Doom (Robert Downey Jr.)
- Major cast: Robert Downey Jr., Chris Hemsworth, Anthony Mackie, Ian McKellen, James Marsden
- Release date: December 18, 2026
- Promo plan (per @MyTimeToShineH, Dec 15, 2025): four short scene teasers, each focused on a different character; one shows Chris Evans' Steve Rogers riding his bike
Bottom line: if Marvel really puts Steve back on screen and pins the Incursion on his time-hop, that is a spicy way to set Doom up as the ultimate fixer-villain — and to pull the entire Multiverse into the fight.