LOS ANGELES - Disney's Marvel Studios on Wednesday revealed the bumper cast of its next "Avengers" film, six years after "Avengers: Endgame" became the highest-grossing movie of all time.

Patrick Stewart and Ian McKellen are among those surprisingly returning to the superhero roster for "Avengers: Doomsday," out May 2026.

They will join a raft of widely expected fan favorites, including Robert Downey Jr. and Chris Hemsworth, a viral five-hour-long video announcement confirmed.

Robert Downey Jr. announces shock Marvel return at Comic-Con

The Marvel superhero films are comfortably the most lucrative franchise in Hollywood history, having collectively made more than $30 billion.

As its title suggests, "Avengers: Doomsday" is intended to be an ensemble blockbuster event in the style of the franchise's pinnacle, 2019's "Avengers: Endgame," which grossed $2.8 billion.

"Endgame" was briefly the highest-grossing movie in history, before the original "Avatar" reclaimed its crown with a theatrical re-release.

Like "Endgame," "Doomsday" will again team up characters and wrap up storylines in a grand finale to more than a dozen preceding Marvel films.

While several returning superheroes -- and the actors playing them -- had been previously announced, Marvel revealed the whole set in a livestreamed video.

Surprises included octogenarian thespians Stewart and McKellen, who previously appeared in early "X-Men" films but were thought to have been written out or recast.

Returning favorites include Hemsworth's Thor, Paul Rudd's Ant Man, and Tom Hiddleston's Loki.

Actors' names were written on the backs of Hollywood-style directors' chairs, with a camera slowly panning from one to the next every 10-15 minutes until ending with Downey Jr. appearing in-person.

Marvel previously announced that the Oscar winner will return to the franchise as the villainous Doctor Doom.

"It all leads to Doom. #AvengersDoomsday is now in production," said an accompanying message.

Downey Jr. kick-started the Marvel big-screen phenomenon back in 2008, playing an entirely different character -- Iron Man.

The franchise went on an unprecedented red-hot box office streak, raking in billions of dollars.

Post-"Endgame," the films have lost some luster, with a dozen movies since receiving mostly weaker reviews.

Box office receipts have also fallen from their peak, though are still enviable compared with almost any other Hollywood franchise.

Wednesday's viral unveiling demonstrates how key to Marvel and Disney the success of "Avengers: Doomsday" -- and 2027 follow-up "Avengers: Secret Wars" -- will be.

The video was watched nearly four million times in its first seven hours.

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© Agence France-Presse