Marvel made fans watch chairs for 5 hours to find out the cast of 'Avengers: Doomsday.' Here's everything we know about the film.

Initially, Kang was set to be the next major villain for the Avengers, but Kang actor Jonathan Majors was fired by Marvel in November 2023 after he was convicted of assaulting his ex-girlfriend.

That same month, the "Loki" season two finale seemingly diminished Kang's role in the MCU when Tom Hiddleston's titular antihero rewrote the timeline, providing an easy route to eliminate Kang from the story.

Then, in July 2024, Marvel announced at the San Diego Comic-Con that Downey Jr., known for playing the beloved hero Iron Man for over a decade, had been cast as Doctor Doom.

While there had been speculation that Downey Jr. might return to the MCU at some point, the announcement was a surprise to many fans, as the actor only left the franchise a few years prior, when Iron Man sacrificed his life at the end of "Avengers: Endgame" to save the universe.

The answer to how this is possible lies in the multiverse — the various dimensions/timelines that are connected together.

Recent Marvel projects have introduced fans to alternate versions of heroes from other universes including Doctor Strange (Benedict Cumberbatch), Scarlet Witch (Elizabeth Olsen), Deadpool (Ryan Reynolds), Wolverine (Hugh Jackman), and more.

So Downey Jr.'s Doom could easily come from another universe to distinguish himself from Iron Man. And the villain wears a metal mask, after all.

Doom is the Fantastic Four's main enemy in the comics, and Marvel Studios head honcho, Kevin Feige, already confirmed that the team's movie, "The Fantastic Four: First Steps" takes place in another universe. Perhaps Tony Stark never got the chance to step up as a hero and chose a darker path in that world.

There have also been versions of Iron Man in the comics that have turned into Doom. Most notably, a young Victor Von Doom body-swapped with Stark as a young man in 2010's "What If? Iron Man: Demon in an Armor #1."

Doom himself even took up the Iron Man mantle in "The Infamous Iron Man" series in 2016. So, there is some precedent for blending their identities.

If the villain does come from another universe, Marvel Studios could still cast another version of Doom for the main MCU on Earth-616 if they wanted someone else to take over the role in the future.

Marvel Studios announced at the 2024 San Diego Comic-Con that siblings Joe and Anthony Russo will direct "Avengers: Doomsday" and the film that follows it, "Avengers: Secret Wars."

Joe and Anthony Russo directed the last two "Avengers" movies, which made over $4 billion in total and are the current second and sixth-highest-grossing movies of all time.

Since leaving Marvel, the Russos have attempted to create their own streaming franchises at Amazon Prime Video and Netflix, but they have not released anything as successful as their Marvel films.

The internet was divided about Downey Jr.'s return, with many criticizing Marvel Studios for playing the nostalgia card and being too safe with their casting choice.

Some fans also said this move would ruin Downey Jr.'s final performance in "Avengers: Endgame" and the legacy of Doctor Doom, one of the most popular Marvel comic villains.

But Rob Mitchell, the director of theatrical insights at Gower Street Analytics, told Business Insider in July 2024 that bringing him and the Russo brothers back is a logical decision.

"The chances are people are going to go, 'This is interesting. What are they doing? I've got to see this. Even if I just want to be able to have an opinion on why.' I get it from a business perspective, I can't really see the downside," he said.

"Fans would've expected big things from an 'Avengers' movie anyway," he added. "And of course, this is the 'Avengers' movie prior to 'Secret Wars.'"

Mitchell noted that people's curiosity about Downey's role in "Doomsday" and "Secret Wars" will draw them in, especially to see if the actor changes his appearance.

"Will he look like Tony Stark or will they do something to make him look different? It's Hollywood, there's plenty of makeup. There's lots of Ryan Reynolds in 'Deadpool & Wolverine' but they don't all look the same."

Downey Jr.'s casting comes amid conversations about whether audiences are tired of the superhero genre. While it's not a new concern, Mitchell said that MCU fatigue hasn't deterred fans.

"Can we really have a conversation about MCU fatigue when 'Deadpool' just made $430 million in four days? This is a film that we are anticipating being only the second R rated film to do a billion dollars. And clearly, that's where it's heading. So you can talk MCU fatigue after that," he said.

Michael Waldron, who wrote "Loki," will be writing the script for the two Avengers movies, which means the film will likely be related to that series.

"Loki," "What If," "Doctor Strange in the Multiverse of Madness," and "Ant-Man and the Wasp: Quantumania" warned that multiversal interactions could lead to a war between universes or the universes colliding into each other.

Though Kang is no longer Marvel's big-picture villain, a collision between different worlds still seems to be the Avengers-level threat that will be faced in the next two films.

Marvel Studios seems to be adapting two major events from its 2015 and 2016 comics, "Time Runs out" and "Secret Wars. In this run of comics, both written by Jonathan Hickman, the multiverse is dying because an alien race called the Beyonders has created living bombs to wipe out everything.

Attempts to kill living bombs lead to multiple earths from these universes colliding, wiping out both universes. The Beyonders' plan succeeds, but Doctor Doom, Doctor Strange, and Molecule Man kill the alien race, steal their power, and create a new world with Doom as the world's god.

Other heroes also survive the decimation using special life raft machines. When they escape, they defeat Doom and restore the universe.

Incursions have already been alluded to in "Doctor Strange in the Multiverse of Madness." While they have the same effect as the comic book, the cause is prolonged multiversal traveling.

It is likely that something before or during "Avengers: Doomsday" kicks off that incursion in the main MCU universe, leading to a battle between multiple worlds. So fans may see even more cameos in the movie outside Downey Jr.'s Doom from one of the other worlds.

Since "Avengers: Endgame," many of the main heroes from previous films have retired or died, and new characters have been introduced to the MCU through various films and Disney+ shows.

In March 2025, Marvel confirmed that "Avengers: Doomsday" is now in production. The studio also announced a slew of "Avengers: Doomsday" cast members via an hourslong livestream.

In addition to Downey Jr., many other major MCU stars will be back: Chris Hemsworth (Thor), Tom Hiddleston (Loki), Paul Rudd (Scott Lang/Ant-Man), and Simu Liu (Shaun/Shang-Chi).

Anthony Mackie (Sam Wilson/Captain America) and Danny Ramirez (Joaquin Torres/Falcon), who most recently reprised their Marvel roles in "Captain America: Brave New World," will return in "Doomsday."

Additionally, the movie will include actors who will star in Marvel's next two films set for release this year, "Thunderbolts*" and "The Fantastic Four: First Steps."

"Thunderbolts"*," set for release on May 2, centers on a ragtag group of assassins and spies who've already appeared in previous MCU projects and must work together on a mission.

Cast members Sebastian Stan (Bucky Barnes/Winter Soldier), Wyatt Russell (John Walker/US Agent), Florence Pugh (Yelena Belova), David Harbour (Alexei Shostakov/Red Guardian), Hannah John-Kamen (Ava Starr/Ghost), and Lewis Pullman (Bob/Sentry) will return in "Doomsday."

After making their MCU debuts this summer in "Fantastic Four," Pedro Pascal (Reed Richards/Mr. Fantastic), Vanessa Kirby (Sue Storm/Invisible Woman), Joseph Quinn (Johnny Storm/Human Torch), and Ebon Moss-Bachrach (Ben Grimm/The Thing) will reprise their roles for "Doomsday."

The "Avengers" movie will feature "Black Panther: Wakanda Forever" stars Letitia Wright (Shuri/Black Panther), Tenoch Huerta Mejía (Namor), and Winston Duke (M'Baku).

"X-Men" actor Kelsey Grammer will also appear in the film, likely reprising his role as Hank McCoy/Beast after his appearance in the end-credits scene of "The Marvels."

He's not the only "X-Men" alum who will be part of "Doomsday." The cast list includes Patrick Stewart (Charles Xavier/Professor X), Ian McKellen (Erik Lehnsherr/Magneto), Alan Cumming (Kurt Wagner/Nightcrawler), Rebecca Romijn (Raven Darkholme/Mystique), and James Marsden (Scott Summers/Cyclops).

Fans of Channing Tatum's performance as Gambit in "Deadpool & Wolverine" will also rejoice in the news that he'll appear in "Doomsday."

The list of 27 cast members noticeably excludes major MCU stars like Mark Ruffalo (Bruce Banner/Hulk), Jeremy Renner (Hawkeye), Benedict Cumberbatch (Stephen Strange/Doctor Strange), Tom Holland (Peter Parker/Spider-Man), Brie Larson (Carol Danvers/Captain Marvel), and Elizabeth Olsen (Wanda Maximoff/Scarlett Witch).

It's likely that additional "Doomsday" actors will be announced at a later date.