We know that Monica is in a universe where the X-Men exist, but pinning down where exactly she goes is tricky. The last time an X-Men universe appeared in the MCU was “Doctor Strange in the Multiverse of Madness.” But we know this isn’t that reality — Earth-838 — because Charles Xavier is still alive here. Hank mentions Charles by name and says that he’s expecting an update on Monica. In “Multiverse of Madness,” Earth-838’s version Professor X (Patrick Stewart) is killed by the Scarlet Witch (Elizabeth Olsen).
The aesthetic of the building around Monica and the return of Kelsey Grammer indicate this could just be the Fox X-Men universe, but there are hints that that’s not the case either. For one, Maria Rambeau wears the costume of the comic book character Binary in the scene — someone who never pops up in the old “X-Men” movies. Beast’s new look has similarities to his “X-Men: The Animated Series” design as well, which some might read as significant due to the upcoming “X-Men ’97” show. That animated series, slated for a 2024 release on Disney+, will be a continuation of “X-Men: The Animated Series,” and it’s believed to have no direct connection to the MCU.
The most likely theory is that this is a new universe, but one that takes heavy inspiration from the Fox movies. The MCU has had no issues in the past bringing back actors from other continuities as slightly different incarnations of their old characters, and that’s probably what’s happening here with Kelsey Grammer’s Hank McCoy.