Though this probably won't be considered much of a spoiler - especially after the release of the Steve Rogers-centric teaser - because this character's return has yet to be officially announced, here's your spoiler warning.
Even though she wasn't actually shown in the first Avengers: Doomsday teaser, Peggy Carter is obviously expected to appear in the movie, and it sounds like Hayley Atwell may have a much bigger role than previous rumors have suggested.
According to scooper Daniel Richtman, "Hayley Atwell will have the biggest role she’s ever had in an Avengers film in Doomsday. She’s not just a cameo, and she actually has a role throughout the movie."
While Rogers will almost certainly rejoin the rest of Earth's Mightiest Heroes in the fight against Doctor Doom and his forces, Carter's role remains a mystery, but we have heard that she will actually play multiple versions of Peggy in Doomsday.
Atwell debuted as Steve Rogers' love-interest in Captain America: The First Avenger, but the British actress got the opportunity to voice a very different take on the hero in the What If...? animated series, before suiting-up as "Captain Carter" (a Captain America variant) for a brief appearance in Doctor Strange in the Multiverse of Madness.
Carter did not last very long in the Doctor Strange sequel, however, and came to a violent end after being cut in half by her own shield by the rampaging Scarlet Witch (Elizabeth Olsen).
Atwell did show interest in getting the chance to do more with her "underserved character" in a recent interview with Den of Geek.
"There are so many things that she could do, there’s so much more I feel I can bring to a character because I’ve developed as time’s gone on," she explained. "What’s so great about having time behind you and having had a 20-year career so far is the development of skill, and I think there’s so much more that Peggy can do. She’s very much an underserved character."
"When she says ‘I know my value and everyone else’s opinion doesn’t really matter,’ it’s because she hasn’t been given the platform that she knows she deserves and that she’s really capable of doing in the world. And so I just think there is just so much more that she can do, and I think she speaks to a modern time, so to be able to take her to that next level as Captain Carter would be phenomenal. Especially with all my Mission: Impossible training. I am ready, let’s go!"
Based on everything we've been hearing, it seems highly likely that Atwell will indeed take up the shield as Captain Carter in Avengers: Doomsday.
Avengers: Doomsday and Avengers: Secret Wars were recently hit with significant delays, with Doomsday now set to arrive in theaters on December 18, 2026, and Secret Wars positioned for December 17, 2027.
Both movies will be directed by the Russo brothers, who also make their MCU return after helming Captain America: The Winter Soldier, Captain America: Civil War, Avengers: Infinity War and Avengers: Endgame.
"Being able to create stories and explore characters within the Marvel Universe fulfilled a life-long dream of ours, and we discovered a powerful connection with audiences in each film that we made. We’re thrilled to collaborate once again with Kevin, Lou and the entire Marvel team to bring this epic adventure in storytelling to new and surprising places for both the fans and ourselves”, said The Russos in a statement after the SDCC panel.
Doomsday will star:
Paul Rudd as Ant-Man, Simu Liu as Shang-Chi, Tom Hiddleston as Loki, Lewis Pullman as Sentry, Florence Pugh as Yelena, Danny Ramirez as Falcon, Ian McKellen as Magneto, Sebastian Stan as Bucky, Winston Duke as M’Baku, Chris Hemsworth as Thor, Kelsey Grammer as Beast, James Marsden as Cyclops, Channing Tatum as Gambit, and Wyatt Russell as U.S. Agent
Along with Vanessa Kirby as Sue Storm, Rebecca Romijn as Mystique, Patrick Stewart as Professor X, Alan Cumming as Nightcrawler, Letitia Wright as Black Panther, Tenoch Huerta Mejia as Namor, Pedro Pascal as Reed Richards, Hannah John-Kamen as Ghost, Joseph Quinn as Johnny Storm, David Harbour as Red Guardian, Ebon Moss-Bachrach as The Thing, Anthony Mackie as Captain America, and, of course, Robert Downey Jr. as Doctor Doom.