Professor X's existence is highly probable in The Marvels' new universe, and his appearance is a near certainty. Magneto, the leader of the Brotherhood of Mutants, is likely to play a pivotal role in the MCU's future. Wolverine's overwhelming popularity ensures his inclusion in The Marvels' new X-Men universe.

After The Marvels' climactic ending, which saw Monica Rembeau fixing a rift in space-time, she found herself transported to another universe entirely, where she encountered Hank McCoy/Beast and Binary, a variant of Monica's mother, Maria Rambeau.
The inclusion of Binary in The Marvels' post-credit scene appeared to lessen the probability that the universe Monica found herself in was the original X-Men franchise. Despite striking similarities between the original trilogy and The Marvels, Professor X's presence was already confirmed to exist in the MCU, making other mutants' appearances less likely at that time.
Secondly, Professor X has already appeared in an MCU property, "Doctor Strange in the Multiverse of Madness," played once more by Patrick Stewart. His version of Professor X in the film was different from any other variant seen in live-action before, but it helped to support further appearances in the MCU's future. Stewart is highly likely to return as Professor X, making it highly likely that he will reprise his role in the Marvel Cinematic Universe.
If the X-Men series has confirmed anything, it is that Charles Xavier and Erik Lehnsherr/Magneto are always entangled in some way. The universe Monica fell into at the end of The Marvels evidently had a strong X-Men organization, complete with the labs and headquarters beneath Xavier's mansion. Therefore, it is incredibly likely that the universe shown in the 2023 MCU film also has a Magneto and his Brotherhood of Mutants. This suggests his future MCU appearance, though which version of the character remains unknown.
If Wolverine's overwhelming popularity were the only factor influencing his inclusion in The Marvels' new X-Men universe, his presence would be far from guaranteed. While Hugh Jackman's return as Wolverine will receive attention in Deadpool 3, the version of Wolverine portrayed in The Marvels would offer a vastly different interpretation of the character. Wolverine's central role in the X-Men franchise, particularly in modern pop culture, would likely contribute to his inclusion in The Marvels' branched timeline, distinct from the character's role in Deadpool 3.
"Jean Grey is an X-Men character whose popularity in both versions of Fox's live-action franchise is undeniable. Her mutant abilities were a significant asset to the franchise, despite the mixed critical reception of the films themselves."
One of the long-running foes of the X-Men, and even an antihero at points in Marvel Comics, is Scott Summers. His role as an antagonist to the X-Men has been a part of the original comic stories for decades, proving how important he is to the world of the mutant heroes. This was also supported by his usage in the Fox X-Men franchise. These two aspects almost guarantee Scott Summers a place in The Marvels' new universe going forward after the film's exciting teases.
Wolverine's presence in the Fox X-Men franchise for decades has overshadowed the importance of Cyclops/Scott Summers as the leader of the mutant superteam in Marvel Comics. This missed opportunity presents an ideal opportunity for The Marvels to rectify the mistakes of the past and give Scott Summers the leadership role he deserves. This new direction would not only honor the comic book source material but also provide the MCU with a compelling new character to add to their expanding universe.
In a similar vein to Scott Summers/Cyclops, the Rogue character in the Fox X-Men franchise faced similar mistreatment compared to the fan-favorite character. While she played an important role throughout the original trilogy, elements of her comic book character were drastically altered in the live-action adaptation, leaving Rogue significantly inferior to her Marvel Comics counterpart. This could be rectified by focusing more on her overall arc and connection to Carol Danvers in the MCU's new X-Men universe.Like the other mutants on this list, Storm was a highly popular character in Fox's X-Men universe. Her immense popularity stems from her equal level of iconic status within the Marvel Comics universe, with her presence in the MCU being a clear possibility. If the Marvel Cinematic Universe smartly capitalizes on the most popular characters from the two Fox X-Men timelines, Storm will undoubtedly be a member of the MCU.
As one of the most formidable mutants in the X-Men movie franchise and Marvel Comics, Storm is a character likely to appear in the Marvels' universe. Ororo Munroe is an immensely powerful, widely beloved, and iconic character. While her appearance in something like Deadpool 3 is possible, her central role in the Marvels' universe is a highly probable outcome. This would rectify the somewhat underserved characterization of Storm in the second Fox X-Men trilogy while introducing an incredibly powerful being to the MCU.
While Quicksilver has already made an appearance in the MCU, its popularity is undeniable, with the character's captivating superspeed sequences in the Fox X-Men films remaining a highlight of the franchise, despite the drop in quality of the movies.
Key Release Dates:
Deadpool 3: 2024-07-26 Captain America: Brave New World: 2025-02-14 Marvel's Fantastic Four: 2025-05-02 Marvel's Thunderbolts: 2025-07-25 Blade (2025): 2025-11-07 Avengers: The Kang Dynasty: 2026-05-01 Avengers: Secret Wars: 2027-05-07