Apart from Professor X (Patrick Stewart), Doctor Strange 2 Super Bowl trailer revealed the surprising return of Stewart as Charles Xavier, although whether it's the same version from Fox's X-Men movies or another multiverse variant remains to be seen. Nonetheless, the tease holds the promise of greater things to come, which continues the MCU's use of the multiverse as a means of bringing back characters and actors who've long departed iconic roles.
This, of course, was most prominent in Spider-Man: No Way Home, which brought back Tobey Maguire and Andrew Garfield's versions of Peter Parker, alongside villains from both Sam Raimi's Spider-Man trilogy and Marc Webb's two The Amazing Spider-Man movies. There was even room, briefly, for Charlie Cox's Daredevil, which could lead to bigger things, while there could've been more returning characters in the mix too, with concept art showing plans for Mysterio (Jake Gyllenhaal) to appear. No Way Home's cameos and returning heroes and villains showed just what's possible in the MCU's multiverse, but Doctor Strange 2 could raise the bar even higher.
Spider-Man: No Way Home didn't fully use the multiverse, which represents a key difference between that movie and Doctor Strange 2. In No Way Home, it was a plot device in order to bring back Maguire, Garfield et al, and to explore the identity and heroism of Tom Holland's Spider-Man. In Doctor Strange in the Multiverse of Madness, the multiverse is the plot, which means the movie needs to more completely dive into it and what that means. In truth, variants are only a small part of it, since the idea of the multiverse should mean endless possibilities, untold dangers, and a whole lot of chaos, but it does mean Doctor Strange 2's cameos can go far, far beyond what No Way Home did, with the only limitations based on who Marvel can and can't get to return.
Still, Doctor Strange in the Multiverse of Madness' cameos present their own challenges to overcome, not least in of how they're used and how many are involved. Spider-Man: No Way Home's cameos were fan-service but, with the exception of perhaps Daredevil (who has a long history with Spidey in the comics, but not on the big screen) the returning actors were all part of a celebration of Spidey. It tapped into 20 years of audience love for the best (and worst) Spider-Man movies and characters, but Doctor Strange in the Multiverse of Madness has a different approach. Yes, Stewart has played Professor X for over 20 years, but the movie can draw upon any and all Marvel movies, lacking the more specific context of No Way Home. That's exciting and potentially great, but also means this could very much become a movie eaten alive by its own cameos.
So far, Doctor Strange 2's rumored cameos run the full gamut of Marvel movies and universes, with talk or theories of MCU characters like Loki and Monica Rambeau, recastings of Fantastic Four characters (such as John Krasinski as Mister Fantastic), another return for Maguire's Spider-Man, and even Tom Cruise as Iron Man. If even half of the cameos expected in Doctor Strange in the Multiverse of Madness come to , it'll be one of the biggest, craziest, and weirdest comic book movies to date, even way beyond what Spider-Man: No Way Home achieved. There's promise in that, and Sam Raimi and the MCU's respective track records with superhero movies are worth trusting in, but No Way Home worked because the cameos added so much heart, emotion, and served the story, which Doctor Strange in the Multiverse of Madness' must do as well.