The X-Men Will Show Up in Avengers: Doomsday. Here’s What That Means for the MCU

Marvel revealed that the X-Men are officially joining the Marvel Cinematic Universe in Avengers: Doomsday, out May 6, 2026. Fans who watched a livestream video for five hours had to wait as the camera ever so slowly panned over a series of chairs with actors' names on them.

Some revelations weren't revelations at all, especially if you've watched the recent Marvel movies. Of course Sebastian Stan will return as Bucky Barnes, the character he's been playing in these movies for 14 long years. Yes, we expected Simu Liu's Shang-Chi to feature in the next Avengers film. What's the point of introducing the Fantastic Four (played by Pedro Pascal, Vanessa Kirby, Ebon Moss-Bachrach, and Joseph Quinn) this summer if they're not going to play a key role in the team-up films? And even casual fans probably saw that Marvel studios announced last year that Robert Downey Jr. was returning to the MCU—not as Iron Man but as the villain Doctor Doom, likely an alternate universe version of Tony Stark who has broken bad.

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But a few names came as a surprise. First came Kelsey Grammer, who played Beast in the early 2000s X-Men movies produced by 20th Century Fox. (Disney and Marvel Studios have since acquired the rights to the X-Men franchise.) Inevitably, Patrick Stewart and Ian McKellen, who made the characters of Professor X and Magneto famous on the silver screen, followed, as did Alan Cumming, Rebecca Romijn, and James Marsden, all key players in that franchise. Even Channing Tatum, who never appeared in the many X-Men movies but played the mutant Gambit in last year's Deadpool and Wolverine, popped up. So the original X-Men will finally appear in an Avengers movie.

Avengers: Doomsday will mark the return not only of Downey Jr. to the MCU but Anthony and Joe Russo, the directing team behind Avengers: Infinity War and Avengers: Endgame. Marvel Studios, which has been in a bit of a box-office slump, are hoping that the previously lucrative pairing of the Russo brothers and Downey Jr. will draw audiences to theaters—and throwing in iconic X-Men characters can't hurt either. Plus, these films have a reputation for having a few surprises up their sleeves.

Notably missing from the casting announcement were a few key members of the Avengers team, including Tom Holland's Spider-Man, Elizabeth Olsen's Scarlett Witch, Mark Ruffalo's Hulk, and Benedict Cumberbatch's Doctor Strange. Nor did key X-Men characters Deadpool (Ryan Reynolds) or Wolverine (Hugh Jackman) pop up in the cast list despite the success of Deadpool and Wolverine last year. Any of those characters could still make an appearance in the movie—Marvel loves a twist—or the next Avengers film, Avengers: Secret Wars.

The Russos have remained tight-lipped about the plots of both Doomsday and Secret Wars. But Marvel Studios has been seeding the idea of a multiverse into its TV shows and films: Spider-Men from multiple universes joined forces in Spider-Man: No Way Home; Loki skips across universes in his TV series. Deadpool visited many universes in Deadpool and Wolverine to find a version of Wolverine who would help him save the world. And Doctor Strange had to do battle with versions of himself from other universes in Doctor Strange in the Multiverse of Madness. Indeed, Stewart made a cameo in that film as a version of Professor X who—spoiler alert—is killed by Scarlet Witch. (That's not the professor's first on-screen death: A version of him also died in Logan.)

Multiverse of Madness hinted that parallel universes will collide—pitting their inhabitants against one another for survival. Fans are speculating, based on comic-book storylines, that the movies will pit superhero against superhero with Doctor Doom orchestrating the chaos. It's possible we will see a battle between the X-Men and Avengers. Who knows where the Fantastic Four will land when the battle lines are drawn. It would be a neat solve for a difficult plot problem. Ushering the X-Men into the Avengers franchise has been a tricky proposition. After all, if the X-Men existed all this time in the same universe as the Avengers, where were they when Loki attacked earth? Or Ultron? Or Thanos? They were off in another universe!

But the existence of the multiverse also complicates this casting announcement. Just because a familiar actor's name was listed on a chair doesn't necessarily mean that that actor is taking on their previous role. After all, Robert Downey Jr. will play Doom, not Iron Man. For all we know, Ian McKellen could be an alternate universe Hulk. (Anything is possible!) Here is everyone listed on the cast list for Avengers: Doomsday and who we think they will play based on their previous films.

Hemsworth has long played Thor, now the only surviving, non-retired member of the original Avengers team. Fans will be eager to see how he will react to beholding a Doctor Doom who looks exactly like his old buddy Tony Stark.

Vanessa Kirby is making her MCU debut as Sue Storm, a.k.a. Invisible Woman, in this summer's Fantastic Four. The new movie about Marvel's first family is set in an alternate universe to the one in which the Avengers we know and love operate. The inclusion of Sue and the other Fantastic Four team members suggests there will be a collision of worlds.

The new Captain America made his debut in this spring's Captain America: Brave New World after Chris Evans' Steve Rogers handed him the shield at the end of Avengers: Endgame.

Sebastian Stan has played Steve's best buddy Bucky, a.k.a. the Winter Soldier, for over a decade. He had a cameo in Brave New World in which he announced he was running for office. And the newly-minted politician will appear in this summer's Thunderbolts* about a ragtag group of anti-heroes kind of replacing the Avengers.

Letitia Wright's Shuri took over the mantle of Black Panther from her brother T'Challa (played by Chadwick Boseman before he passed away) in Wakanda Forever.

Paul Rudd previously starred in three Ant-Man movies as the superhero who can shrink to subatomic size.

Wyatt Russell debuted as the antihero U.S. Agent in the Disney+ show Falcon and the Winter Soldier. The man who took supersoldier serum but proved unworthy of Captain America's shield now operates as a hit-man of sorts and will appear in this summer's Thunderbolts*.

Mejia debuted as the villain Namor in Wakanda Forever and was responsible for the death of Queen Romanda (Angela Bassett) in that film. Shuri comes to an uneasy truce with Namor at the end of that film, but Namor has teamed up multiple times with Doctor Doom in the comics and could prove dangerous in this new film.

Another member of the Fantastic Four team, Moss-Bachrach plays The Thing, a massive rock of a being and the strongest member of that quad.

Liu is making his long-awaited return to the MCU after the debut of his film Shang-Chi in 2021. Last we saw Shang-Chi he was setting off on an adventure with sorcerers.

Pugh's Yelena Belova made her debut as the little sister of Natasha Romanoff (Scarlett Johansson) in Black Widow. Like her sister, Yelena is a trained assassin. Now mourning the death of her sister, Yelena operates as a gun-for-hire in Thunderbolts*.

The inclusion of Grammer's name was our first hint that the original X-Men cast from the 2000 film would be returning to the big screen. Grammer made a cameo as Beast in the post-credits scene for The Marvels. Now, it seems, he'll be joined by several of his fellow X-men.

Pullman is playing a new superhero named The Sentry in this summer's Thunderbolts*.

Sam Wilson's sidekick takes on Sam's old name, The Falcon, in the most recent Captain America movie.

Quinn will make his debut in the MCU as the Human Torch in Fantastic Four this summer. But don't confuse him with Chris Evans' Human Torch who first cropped up in the 2005 Fantastic Four film and made a memorable cameo in Deadpool and Wolverine last year.

Natasha and Yelena's adoptive father operates as the Red Guardian, a sort of U.S.S.R. counter to Captain America. He starred in Black Widow and will appear in Thunderbolts*.

Duke's M'Baku played a central role in both Black Panther films. At the end of Wakanda Forever, M'Baku becomes king of Wakanda, freeing Shuri up to explore her work as a scientist and superhero.

First seen in Ant-Man and the Wasp, John-Kamen's villain-turned-hero Ghost will also appear in Thunderbolts*.

Hiddleston's Loki has gone through many, many, many transformations in the MCU. Sometimes he's a villain trying to conquer earth. Sometimes he's a hero trying to block Thanos from destroying half of all life in the universe. He's "died" and been resurrected several times, and alternate universe versions of him riddle the Loki TV series. Hiddleston's inclusion in this movie promises a reunion between Loki and his brother, Thor.

Fans were excited to learn that the original Professor X would return to lead the X-Men into whatever battle they must face in this Avengers film. Versions of Professor X have died in both Logan and Doctor Strange in the Multiverse of Madness, so who knows which Professor X we will meet in this movie.

Professor X's frenemy Magneto, as originated by the great McKellen, has the potential to play either hero or villain in this film, depending on whether he sees Doctor Doom as a threat to the mutants or a potential savior.

Though he's thriving as the host of The Traitors at the moment, Cumming used to play the powerful mutant Nightcrawler in those original X-Men films. He features in an iconic White House battle scene in X2.

Before Jennifer Lawrence took on the role, Rebecca Romijn brought the shape-shifting Mystique to the big screen.

Marsden is perhaps still best remembered for his portrayal of Cyclops, the Mutant with killer vision who mooned after the ultra-powerful Jean Grey.

Tatum tried for years to make a movie about Gambit, the card-slinging mutant from New Orleans, but the film never came to fruition. Tatum finally got to play a version of the character (with a knowingly incomprehensible accent) in Deadpool and Wolverine last year.

It's notable that Pascal is the penultimate name on this cast list. The actor will play Reed Richards, a.k.a. Mister Fantastic in Fantastic Four this summer. Throughout comics history, Doctor Doom has repeatedly faced off with Reed Richards. They're two of the smartest men in the universe, old friends-turned-mortal enemies. It's likely that if there's a new leader of this Avengers team set to take on Doctor Doom, it's Reed.

As previously announced, Robert Downey Jr. is returning to the MCU to play the ultimate villain, Doctor Doom. He will likely be the main antagonist in both Doomsday (named after him, of course) and Secret Wars, pitting the various heroes against one another in his bid for control.