Warning: Spoilers for Doctor Strange in the Multiverse of Madness.
Patrick Stewart's Professor X made a major cameo in Spider-Man: No Way Home, Doctor Strange in the Multiverse of Madness finally provides the titular sorcerer with his second star vehicle after a six-year gap. Featuring the return of director Sam Raimi to the superhero genre, Multiverse of Madness mostly lived up to its name.
While some did leave the theater wishing Doctor Strange got to explore much more of the vast multiverse, what they did get to see was quite interesting, including a brief glimpse at a world where everyone was made of paint. The bulk of the multiversal travel period was dedicated to Strange and America Chavez spending time in Earth 838, a world in which a different Doctor Strange accidentally caused the destruction of an entire universe. Left to pick up the pieces was a society of powerful leaders called The Illuminati.
The of this Illuminati group included Reed Richards, Maria Rambeau's Captain Marvel, Black Bolt of the Inhumans, Baron Mordo, Captain Carter, and Professor X himself. Audiences didn't really get to know them, as an ultra-powerful Scarlet Witch showed up to stage a massacre. Still, a clue was given as to what universe this Professor X hails from, as when he's first seen onscreen, a quick snippet of the classic Doctor Strange 2's Professor X is from the universe of X-Men '97.
While this Easter egg revelation would be an exciting enough inclusion on its own, the fact that Scarlet Witch kills Professor X in Doctor Strange and the Multiverse of Madness has some concerning implications going forward. Disney+ is preparing to return to the X-Men: The Animated Series universe soon with the X-Men '97 reboot. If this version of Professor X is indeed from that world, it remains to be seen how that will affect the still mostly unclear plot of the animated revival. If it takes place even partially after Doctor Strange 2's ending, Xavier would be dead, but it's highly doubtful he won't be a constant part of X-Men '97. That would necessitate it being set entirely before Multiverse of Madness, perhaps in its titular year.
Even more potentially impactful though is the idea that Earth 838 may itself be the X-Men: The Animated Series universe since it's not implied that the Professor X seen in the MCU had come from off-world. That would mean that the X-Men '97 universe has also lost its Mr. Fantastic, Captain Marvel, Captain Britain, and Doctor Strange, which could greatly affect its timeline moving forward. While it's easy to suggest that X-Men '97 won't acknowledge the events of Doctor Strange in the Multiverse of Madness, it's worth ing that What If? connects to the MCU, so Marvel Studios isn't averse to doing live-action crossovers with animated works.