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Credit: Marvel StudiosThe Marvel Cinematic Universe is heading toward another major shift, and several longtime heroes are navigating next steps as the franchise prepares for its next era. Disney has now confirmed that December 19, 2025, will stand as a pivotal milestone for the MCU.
Arriving in 2026, Avengers: Doomsday is positioned to be one of Marvel Studios’ most ambitious undertakings so far. The film reunites Avengers: Infinity War (2018) and Avengers: Endgame (2019) directors Anthony and Joe Russo, steering the storyline away from its earlier Kang-centric concept and instead placing Doctor Doom in the spotlight, portrayed by Downey Jr. in his highly anticipated MCU return.
Marvel kicked off early 2025 with a “chair reveal” livestream, dropping a massive cast list that included Sebastian Stan (Bucky Barnes), Paul Rudd (Ant-Man), Simu Liu (Shang-Chi), Florence Pugh (Yelena Belova), Tom Hiddleston (Loki), Chris Hemsworth (Thor), Kelsey Grammer (Beast), and James Marsden (Cyclops).
That same reveal cemented the return of several Fox-era X-Men favorites: Ian McKellen (Magneto), Rebecca Romijn (Mystique), Patrick Stewart (Professor X), and Alan Cumming (Nightcrawler), signaling a full-on merging of Marvel’s cinematic universes.
As the cast list grew, several MCU veterans spoke candidly about their absence from the ensemble. Mark Ruffalo, the Hulk since The Avengers (2012), joked on The Tonight Show Starring Jimmy Fallon, “They decided that it was better to get rid of me than for me to tell the end of the next movie.”
While Ruffalo isn’t part of Doomsday’s lineup, he is already confirmed for Destin Daniel Cretton’s Spider-Man: Brand New Day (2026).
Brie Larson, meanwhile, has remained intentionally vague when discussing her future as Captain Marvel. On The View, when asked whether she would show up in Avengers: Doomsday, she answered, “Thank you for asking, and you know I can’t answer.”
Her careful response added fuel to continuing speculation that Carol Danvers may be involved in ways not yet revealed. Back in 2024, Larson told reporters, “I don’t have anything to say about that,” and in June 2025, posted a mysterious photo of herself beside the words “AVENGE” and “DANVERS.”
Larson’s last MCU appearance came in The Marvels (2023), which concluded with Teyonah Parris’s Monica Rambeau stranded in another dimension and Carol promising to bring her home.
Disney’s next major entry in the Avatar saga, Avatar: Fire and Ash (2025), helmed by director James Cameron, hits theaters on December 19, 2025. Multiple reports suggest Disney plans to use the release as a launchpad for the debut trailer of Avengers: Doomsday.
“Collider has learned from multiple sources that the first footage from the MCU’s next big team-up film is scheduled to be attached to the latest installment of one of Disney’s other blockbuster franchises, Avatar: Fire and Ash,” the outlet reported.
If so, the teaser would arrive exactly one year before Doomsday’s currently scheduled premiere date of December 18, 2026. The move would mirror the release approach of Christopher Nolan’s The Odyssey teaser, which appeared a year ahead of its debut in front of Jurassic World Rebirth (2025) and focused on a character-driven moment rather than an overview of the film’s larger scope.
Now, just weeks after those reports, it has been confirmed that Avengers: Doomsday will be dropping in front of the Avatar threequel.
Avengers: Doomsday trailer is confirmed to be [attached] on Avatar 3.
Avengers: Doomsday trailer is confirmed to be attatched on Avatar 3. pic.twitter.com/zpSYe4bopQ
— MikeOnTheGrid 🥏 (@MikeTheProgram) December 11, 2025
I should also add that this trailer is 1 minutes and 27 seconds long. Contrary to the 60 seconds that was rumored.
I should also add that this trailer is 1 minutes and 27 seconds long. Contrary to the 60 seconds that was rumored.
— MikeOnTheGrid 🥏 (@MikeTheProgram) December 12, 2025
It makes sense that Disney and Marvel would use something as big as Avatar: Fire and Ash to launch the Doomsday trailer, but it will irk some fans who aren’t planning on going to see the latest James Cameron movie or who see the trailer being used as a ploy to get people in Avatar screenings.
New promotional artwork for Avengers: Doomsday has sparked conversation surrounding the futures of Captain Marvel and Thor. A high-resolution piece unveiled at the Walt Disney Studios Marketing Expo in Shanghai offered an up-close look at Doctor Doom’s armor, featuring two distinct symbols on the cloak fasteners.
One emblem echoes Captain Marvel’s starburst insignia, while the other resembles Thor’s hammer, Mjolnir. The balanced placement has led many fans to speculate that these aren’t simple artistic choices but potential trophies from Multiversal variants of the heroes.
While the imagery could be purely stylistic, the details have increased curiosity about Doom’s role, hinting that his rise may represent one of the most dramatic shifts the MCU has attempted so far.
Marvel Studios is continuing to recalibrate as it heads into Phase Six. 2025’s The Fantastic Four: First Steps opened strong before experiencing a steep second-weekend decline, highlighting the studio’s ongoing challenge of maintaining long-term audience engagement.
Even so, Marvel president Kevin Feige and the Russo brothers have shared that Avengers: Doomsday and the follow-up, Avengers: Secret Wars (2027), will act as a creative refresh for the MCU—one expected to place the X-Men at the forefront while redefining the franchise’s central roster.
With Robert Downey Jr.’s Doctor Doom positioned as the primary antagonist and a cast pulling together characters from multiple eras of Marvel storytelling, Avengers: Doomsday could serve as a defining turning point for the entire franchise.
How do you feel about the Avengers: Doomsday trailer coming soon? Let Inside the Magic know in the comments below!