A new era for mutant-kind begins on screen. Over the course of a five-and-a-half-hour livestream that played out on social media Wednesday, Marvel Studios announced the first wave of casting for Avengers: Doomsday. The 27 names ran the gamut from OG franchise star Chris Hemsworth to rising heavyweights like Florence Pugh and Anthony Mackie to some of the newbies like Pedro Pascal and his fellow Fantastic Four castmates. But the news came with an X factor.

Patrick Stewart‘s name emerged, marking the second time the actor would reprise his Professor Xavier role in the MCU since Doctor Strange in the Multiverse of Madness. Then the camera panned further and revealed Ian McKellen, Alan Cumming, Rebecca Romijn, and James Marsden — who all starred with Stewart in the X-Men film series of yesteryear — are also coming back into the Marvel fold. And they’re joined by Channing Tatum, who played another X figure in last summer’s Deadpool & Wolverine.

It’s one of those moments comic fans have been patiently waiting to see come together: the official arrival of the X-Men team of mutants into the fabric of this sprawling pantheon of characters. It’s a journey that began in December 2017, when the Walt Disney Co. first announced plans to acquire 21st Century Fox properties, including the onscreen rights to the X-Men, Fantastic Four, and all the other Marvel characters owned by Fox at the time. But even as the deal finally closed in March 2019, we’re only just getting to this point six years later. Here’s a glimpse of how it all came together.

First steps

Even when Disney first announced the acquisition, certain roadblocks prevented them from outwardly dropping a character like Wolverine alongside Thor, Captain Marvel, and the rest of the Avengers crew. Kevin Feige, the president of Marvel Studios, previously told Entertainment Weekly in a 2024 interview that there were certain logistical realities with the deal they had to face.

“I don’t want to get into corporate acquisition legal laws or whatever. I don’t understand them, but there’s a lot of ’em,” Feige said. “It took a long time between whenever [the acquisition] was announced to it all getting done, so [the characters] weren’t really in our sandbox for a very long time after that first announcement happened.”

So, plans started slow. With 2021’s WandaVision, the first MCU TV series for Disney+ expanded upon Elizabeth Olsen‘s Wanda Maximoff to get into her comic book roots as a reality-bending witch, though the show didn’t get into the character’s connections to the X-Men as the daughter of Magneto. Still, they found ways to play in the sandbox. Evan Peters, who previously played speedster Quicksilver in Fox’s X-Men: Days of Future Past (2014) and X-Men: Apocalypse (2016), made a guest appearance as Ralph Bohner, a resident of the town of West View who was spelled by Kathryn Hahn‘s Agatha Harkness to act as Wanda’s brother Pietro. They didn’t call him Quicksilver and made no reference to mutants, so it allowed the franchise to bring in a figure from the past Fox franchise in an “if you know, you know” capacity.

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The Falcon and the Winter Soldier followed that same year with a similar approach. Mackie’s Sam Wilson and Sebastian Stan‘s Bucky Barnes traveled on a mission to Madripoor, a location in Southeast Asia from many X-Men stories of Marvel comics, particularly in ones involving Wolverine. It wouldn’t be until a full year later that more overt references began popping up in various MCU titles.

Cameos

The most obvious one was Stewart’s presence in the Doctor Strange sequel. This wasn’t the same Charles from the Fox movies, but one from a different reality in which he serves as a prominent member of the Illuminati, a secret society watchdog group of heroes. That film also involved John Krasinski as Reed Richards/Mr. Fantastic, a member of the Fantastic Four super-team and another character once owned by Fox.

Stewart signaled in an interview that more might be in the works, saying, “There is potential maybe for a reappearance of Professor Xavier.” Did he know then what we know now about Avengers: Doomsday? It’s hard to say.

Also in 2022, the MCU got its first mention of the word “mutant,” used to describe Kamala Khan (Iman Vellani) in the Disney+ series Ms. Marvel, and later that year with Namor the Submariner (Tenoch Huerta Mejia) in Black Panther: Wakanda Forever. And the references kept coming. She-Hulk: Attorney at Law (2022) included a Wolverine Easter egg on a news site with an article titled “Man Fights With Metal Claws in Bar Brawl,” then broke the fourth wall in the finale and asked Feige himself for the X-Men.

With all the self-referential gags going on in She-Hulk, it was difficult to determine what exactly was considered canon. But by 2023, the floodgates really opened up and answered some of those questions. Following Stewart, Kelsey Grammer made his first return appearance as Beast in a post-credits scene attached to The Marvels. That bit told us a couple of things: the X-Men exist (or at least some version of them do, if not the exact one made famous by the Fox movies), but they don’t exist in the reality we’ve come to know on screen. They exist in alternate dimensions. Grammer’s Beast appears in one particular reality where Maria Rambeau (Lashana Lynch), Carol Danvers’ BFF in the main universe, is a mutant called Binary who serves as a member of the X-Men.

Then, of course, there was 2024’s Deadpool & Wolverine.

Going full X-force

Many actors from previous Fox-era X-flicks reprised their roles in that movie, with Ryan Reynolds‘ Wade Wilson and Hugh Jackman‘s Logan leading the charge. Joining them were Aaron Stanford as Pyro (from X2, X-Men: The Last Stand), Tyler Mane as Sabretooth (X-Men), Dafne Keen as X-23 (Logan), and a handful of non-X-Men acting veterans playing X-Men-related characters. Spotted were variations of Toad (X-Men), the teleporting Azazel (X-Men: First Class), the near-indestructible Juggernaut (X-Men: The Last Stand, Deadpool 2), Lady Deathstrike (X2), Callisto (X-Men: The Last Stand), Psylocke (X-Men: Apocalypse), and Quill (X-Men: The Last Stand).

The biggest new addition — not including the other non-X cameos — was Tatum. In the days of Fox’s X-Men reign, the actor was set to appear in a standalone movie as Gambit, a.k.a. Remy LeBeau, the Cajun card-slinging mutant with the ability to turn potential energy into kinetic energy, thereby transforming virtually anything he touches into explosives. Tatum even appeared at San Diego Comic-Con one year to pose next to his fellow X-Men franchise costars during a Hall H panel. However, with Disney’s takeover of Fox, that was one project lost to history…until the third Deadpool movie. Reynolds teased to EW that Marvel became “obsessed with him in that role.”

Ahead of its release last July, Feige told EW the movie is “really when it all starts” to bring in Marvel’s mutants and the X-Men to the MCU. The multiverse became the key to unlocking how these characters would naturally fold into the ever-expanding world of the Avengers. Much like Grammer, Stewart, and everyone in Deadpool & Wolverine, they would come from parallel dimensions.

The animated What If…? series leaned into that concept further by bringing in Storm, another prominent member of the X-Men with power over the weather. Alison Sealy-Smith, the Storm voice actress from X-Men: The Animated Series and last year’s X-Men ’97 (not officially part of the MCU), returned to voice her.

Appearing over video conference at a convention in Singapore in November, Feige made the plan clear: “I think you’ll see that continue into our next few movies and some X-Men players that you might recognize. And then right after that, the whole story of Secret Wars really leads us into a new age of mutants and of the X-Men. And, again, one of these dreams come true that we finally have the X-Men back at Marvel Studios.”

Cumming had some fun with his Nightcrawler announcement in Wednesday’s Avengers: Doomsday reveal. The Traitors host leapt into the frame of a video he shared to Instagram, emulating his X-character’s physicality. “Never say he never,” he captioned the footage.

“She’s back. True. Blue,” Romijn wrote in her own Instagram post, marking the return of Mystique after nearly 20 years since her last appearance. (Not counting the 2011 cameo in X-Men: First Class.)

Marvel also signaled that they aren’t done with the casting reveals for Doomsday, so there may even be more X-Men figures joining the fray ahead of Secret Wars. The official Marvel social account on Instagram replied to a Robert Downey Jr. comment to say, “There’s always room for more.”

Avengers: Doomsday, now in production, will first hit theaters on May 1, 2026, followed by Avengers: Secret Wars on May 7, 2027. And, though the film hasn’t officially been announced by the studio or scheduled for release, Marvel is working on developing a new X-Men movie as part of the MCU lineup. Feige told the Omelete that it would likely fall sometime after Secret Wars.

“It all leads to Doom” seems to be the new tagline for Avengers: Doomsday, but we now know the MCU’s real destination.