The X-Men will eventually come to the MCU and one theory posits Doctor Strange in the Multiverse of Madness will be the movie that sets them up through Scarlet Witch. Speculation has been swirling as to how the X-Men could be included, pretty much since the MCU properly began. Initially, it was a question of rights, as then-20th Century Fox owned the film rights to the X-Men and continued making films with the property well into the tenure of the MCU. When Disney bought 20th Century Fox outright, the legal question came to a close, but all that really did was change which elephant occupied the room.
With 20th Century Fox still cranking out X-Men movies before Disney as recently as 2019's Dark Phoenix, the MCU had gone for just over a decade without even the concept of mutants being present. Still, such a deal wouldn't be made without Marvel having some sort of plan in mind. Now with the reveal of Professor X in the Doctor Strange 2 trailer, it seems like the reality of the X-Men appearing in the MCU is closer than ever. However, there's still the question of how it will all come to pass.
Related: Marvel Already Did Scarlet Witch’s Upcoming Story In Endgame (But It Can Do Better)
The upcoming Doctor Strange in the Multiverse of Madness already seems primed to introduce the concept of mutants. However, the bringer of this change won't actually be Doctor Strange himself. All the signs point to a post-WandaVision Scarlet Witch being the source of this massive shift for the MCU and the perfect vessel to bring the X-Men into the MCU, even if indirectly.
In the comics, Wanda Maximoff is a mutant whose abilities essentially amount to probability manipulation and WandaVision already began soft-retconning her MCU origin story.
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