(Warning: This post contains potential spoilers for Marvel’s Avengers: Doomsday.)
Steve Rogers/Captain America (Chris Evans) will be a key character in the Avengers: Doomsday plot.
According to an insider’s leaked report, Steve Rogers going back in time to live happily with Peggy Carter is to be a major plot point in Avengers: Doomsday, as he created the incursions in the multiverse. Robert Downey Jr.‘s Doctor Doom wants him dead.

Steve not only chose to stay in the past with Carter, but he also started changing things. So, “for the multiverse to live, Steve has to die.”
Marvel Studios has not officially announced Chris Evans yet, but he filmed Avengers: Doomsday secretly. Evans’ codename during filming was “Luke Cage.” Also, during filming at Windsor Great Park, a leaked set image revealed a 1960s-style Luke Cage house that had been built.

According to Alex (via The Cosmic Circus), Downey Jr.’s Doctor Doom is similar to how Thanos was the main character in Avengers: Infinity War. He sees Multiverse incursions as a threat and plans to stop them by using young Franklin Richards.
Avengers: Doomsday will feature Earth-616, Earth-828, the Earth-10005 X-Men Universe, and an Earth completely destroyed by an incursion. Shuri discovers the incursions and alerts the Avengers.
In Avengers: Doomsday, the MCU begins the beginning of the end. As the multiverse nears total collapse, the Avengers assemble to face their greatest challenge yet—incursions, catastrophic collisions between realities that could destroy the entire multiverse. Earth’s Mightiest Heroes must race against time to save their reality while confronting the powerful figure behind it all—Victor Von Doom (Downey Jr.).
Directed by the Russo brothers from a screenplay by their longtime collaborator Stephen McFeely, Avengers: Doomsday is now being co-written by McFeely and Michael Waldron, the creator and head writer of the Loki series. The film features cinematography by Newton Thomas Sigel (Bohemian Rhapsody, X-Men: Days of Future Past) and production design by Kasra Farahani.
The official cast members of the film include Downey Jr. as Doctor Doom, Paul Rudd as Ant-Man, Simu Liu as Shang-Chi, Tom Hiddleston as Loki, Florence Pugh as Yelena Belova, Danny Ramirez as Falcon, Sebastian Stan as Bucky Barnes, Winston Duke as M’Baku, Chris Hemsworth as Thor, Letitia Wright as Black Panther, Tenoch Huerta Mejía as Namor, Anthony Mackie as Captain America, David Harbour as Red Guardian, Wyatt Russell as U.S. Agent, and Hannah John-Kamen as Ghost. Ian McKellen as Magneto, Patrick Stewart as Professor X, Rebecca Romijn as Mystique, James Marsden as Cyclops, Kelsey Grammer as Beast, Alan Cumming as Nightcrawler, and Channing Tatum as Gambit. Pedro Pascal as Reed Richards (Mr. Fantastic), Vanessa Kirby as Sue Storm (Invisible Woman), Joseph Quinn as Johnny Storm (Human Torch), Ebon Moss-Bachrach as Ben Grimm (The Thing), and Lewis Pullman as Sentry.
Produced by Kevin Feige, Louis D’Esposito, and Russo Brothers will produce through their AGBO banner.
Avengers: Doomsday will be released in theaters and IMAX across the United States on December 18, 2026.