Marvel fans weren't sure whether or not they'd ever see the Avengers in collaboration with characters from the X-Men and Fantastic Four franchises.

The rival film studio 20th Century Fox has long owned these rights till now.

After purchasing the rights to several Marvel heroes, Disney recently purchased film rights to the X-Men, Fantastic Four and other heroes.   

Because of this, they have introduced Mutants into the Avengers' universe.

Now, Patrick Stewart will be playing the role of X-Men leader Charles Xavier in Doctor Strange in the Multiverse of Madness.

This was cleared when Stewart showed up to Comic-Con dressed as a superhero, which he later revealed while promoting the film on The Late Show with Stephen Colbert. 

He's sporting a traditional costume from the '90s animated series, which is set to reboot with Marvel Studios' X-Men '97​​​​​, depicting a time before the formation of this much-beloved team.

With Professor X returning in the Multiversal blockbuster and possibly cameos from other X-Men, this film could be the first in the MCU to utilise the name "Mutant."