The biggest Avengers Doomsday Theory just got confirmed by the director. Anthony Russo, one half of the Russo Brothers, has officially stated that Steve Rogers’ time travel at the end of Endgame is what triggers the entire plot of Avengers: Doomsday. One Avengers Doomsday Theory down. A hundred more to go.
Here’s what Russo said. The new scene in Endgame Encore shows Loki arriving at Peggy Carter’s door. He says he can help both of them. That moment, according to Russo, is where the Doctor Doom movie is born. Steve Rogers went back in time to live with Peggy. He created a branch timeline. He didn’t just retire. He broke something. That Avengers Doomsday Theory is now canon.
The rest of the film is still a mystery. The most popular Avengers Doomsday Theory right now is that Doctor Doom is a Tony Stark variant. The Endgame Encore post-credits scene with Doom hammering his mask supports that. Another Avengers Doomsday Theory says the Hulk will be a villain. The new Encore scene where Doom “collects” Bruce Banner supports that too. The theories are stacking up, and the evidence is piling up with them.
The confirmed cast is absurd. Chris Evans is back as Steve Rogers. Robert Downey Jr. is Doctor Doom. Chris Hemsworth, Pedro Pascal, Florence Pugh, Paul Rudd, Sebastian Stan, Anthony Mackie, and the entire Fantastic Four are in it. The X-Men from the old Fox movies are showing up too. Patrick Stewart. Ian McKellen. James Marsden. Kelsey Grammer. Channing Tatum as Gambit. This is the biggest cast Marvel has ever assembled.
The Avengers Doomsday Theory about Doom winning is the one that scares people. If Doom wins, if the multiverse collapses, if Battleworld becomes real, the MCU is entering its darkest chapter. The film is projected to be the highest-grossing movie of 2026. Pre-sales crossed $50 million three months before release. Everyone is watching.
Is there an Avengers Doomsday Theory that will be 100 percent correct? Probably not. Marvel has been playing with misdirection for years. But Russo just confirmed one. That’s rare. That’s a gift. Take it.
Avengers: Doomsday opens December 18. The Avengers Doomsday Theory about Steve Rogers is real. The rest is speculation. For now, that’s enough.