Excitement is building around Marvel Studios’ latest casting news, which has validated a theory I’ve held for a while regarding Avengers: Doomsday. This highly anticipated fifth Avengers installment, set to premiere in 2026, promises an extensive roster of characters, potentially exceeding the 27 confirmed during Marvel’s recent live-stream event. The latest announcements suggest that the film will explore far more than simply an epic face-off with Robert Downey Jr.’s Doctor Doom.
During the five-and-a-half-hour live stream, Marvel officially revealed much of the cast for Avengers: Doomsday, each actor’s name displayed on their respective chairs. Expected returns include Anthony Mackie as Captain America and Chris Hemsworth as Thor, but also joining the fray are several iconic actors reprising their roles from Marvel characters outside the Earth-616 universe—the main reality of the MCU. This revelation has reinforced my strong belief that X-Men will play a significant role in the storyline of Avengers: Doomsday.
Multiple X-Men Join the Roster for Avengers: Doomsday
Professor X, Magneto, Gambit, and More!
The recent post-credits scene from The Marvels introduced Monica Rambeau alongside Kelsey Grammer’s Beast from an alternate reality featuring the X-Men. Coupled with the 2024 release of Deadpool & Wolverine, which confirmed that Fox’s X-Men universe exists as Earth-10005 within the multiverse, I have speculated about the incorporation of X-Men into Doomsday and Secret Wars. Recent casting announcements, however, have dramatically elevated my expectations for their role in the upcoming film.
Alongside Kelsey Grammar’s return as Beast, Marvel has also confirmed the appearances of Patrick Stewart as Professor X and Ian McKellen as Magneto. Additionally, we will see the return of the original Mystique and Nightcrawler: Rebecca Romijn and Alan Cumming, as well as James Marsden’s Cyclops and Channing Tatum’s long-awaited Gambit, who made his debut in Deadpool & Wolverine. This brings the known count of X-Men in Avengers: Doomsday to seven, with the possibility of even more characters being added.
Fox’s X-Men Universe Likely to Supplant the Ultimate Universe
Remixing Marvel Comics’ Final Incursion Before 2015’s Secret Wars
It appears increasingly likely that Fox’s X-Men universe will have a more substantial impact on Avengers: Doomsday than many anticipated. I have speculated for a while that this universe could effectively replace the Ultimate Universe within the MCU as elements from Marvel Comics’ Secret Wars are adapted for the screen. In the 2015 comic crossover, the main Marvel reality and the Ultimate Universe (Earth-1610, home to Miles Morales) were the final two worlds standing in the multiverse before being consumed by incursions.
Theory: Doomsday as an Avengers vs. X-Men Multiverse Showdown
“Avengers Assemble”versus “To Me, My X-Men”
If my theory is correct, Avengers: Doomsday could essentially evolve into a secret Avengers vs. X-Men movie. This aligns with what the Russo brothers hinted at years ago — they expressed interest in returning to the MCU for this concept alongside Secret Wars. Currently, signs indicate that they may bring both ideas to fruition, with the multiversal aspect adding layers to the conflict rather than replicating the original comics’ struggle over the Phoenix Force.
“The likelihood of an Avengers versus X-Men confrontation in the MCU seems to be increasing, particularly as Avengers: Doomsday attracts even more members of the mutant cast…”
It would certainly be thrilling to see the Avengers and X-Men clashing for the survival of their own worlds, particularly before Doctor Doom intervenes for his own motives. Additionally, this concept correlates with The Leader’s cryptic remarks during the post-credits scene of Captain America: Brave New World, where he warned Sam Wilson of forthcoming “other worlds/heroes”that will need to be reckoned with. Overall, the stage seems set for a monumental confrontation between the Avengers and rising mutant forces as more characters potentially join Avengers: Doomsday.
Mark your calendars: Avengers: Doomsday is set to hit theaters on May 1st, 2026.