Robert Downey Jr. returns to the MCU with other confirmed actors including stars Chris Hemsworth and Tom Hiddleston, 'X-Men' stars like Patrick Stewart and Ian McKellen, and a good chunk from the studio's 'Thunderbolts.

Marvel has announced the return of some Marvel Cinematic Universe (MCU) stars in 2026's "Avengers: Doomsday," including Chris Hemsworth as Thor, Anthony Mackie as Captain America, Sebastian Stan as Bucky Barnes and Tom Hiddleston as Loki.

When the Marvel Cinematic Universe released its first tentpole film The Avengers in 2012, its success (grossing $1.5 million worldwide) set off a phase of superhero mania — where the least connected of films could get people to fill seats at the mere hint of a new casting or surprise cameo.