Doomsday. We know that because a bunch of them, including Patrick Stewart and Ian McKellen, are confirmed for the gigantic MCU crossover. Their presence is fueling a lot of theorizing, and some fans think they may have spotted the Avengers vs.

Who will all these heroes face off against this entry to the Avengers franchise? None other than Robert Downey Jr., who's stepping into a new role with a fresh mask as the villainous Doctor Doom. Downey Jr., of course, played Tony Stark/Iron Man in the previous "Avengers" films.