Seven years after Avengers: Endgame broke box office records – and the hearts of fans around the world – Marvel has put together yet another epic big-screen crossover event.

Avengers: Doomsday marks the fifth instalment in the Avengers franchise, and is expected to be the cinema event of 2026, bringing back some of our favourite characters and introducing a whole new roster of superheroes to the MCU.

With months to go until the release, fans already have plenty of questions about the upcoming release. Namely, who is in the star-studded cast? What exactly is the plot of Avengers: Doomsday? And how did one actor’s abrupt departure lead to the entire film being rethought?

Here’s everything we can tell you about Avengers: Doomsday so far…

Marvel has already teased that Avengers: Doomsday will mark the beginning of the end for its multiverse saga, which began in 2021 with the TV series WandaVision.

Although there is official plot details are still being kept under wraps, the studio has said that the Phase Six movie sees “beloved heroes from three distinct universes” embarking on “a deadly collision course” and facing “an existential threat unlike anything they’ve ever encountered”.

In other words, we should expect to see characters from The Avengers, Thunderbolts, X-Men and Fantastic Four all teaming up to defeat the evil Doctor Doom.

Fans are already theorising that this will create “Battleworld”, a patchwork planet from the Marvel comics, which is created from fragments of destroyed realities.

“We’re not talking too much about story, but I think people know that the story of Doomsday is inspired by a very famous comic run in which universes are colliding and Earths encounter one another and different timelines encounter one another,” Marvel Studios chief Kevin Feige teased to Entertainment Weekly in April this year.

Frankly, it might be quicker to list who from the MCU isn’t set to appear in Avengers: Doomsday.

In March last year, Marvel hosted a mammoth five-hour livestream where they slowly revealed the sprawling cast of Avengers: Doomsday, which includes some of the biggest names in Hollywood – and pretty much anyone who has ever appeared in a Marvel film.

Chris Hemsworth, Anthony Mackie, Paul Rudd, Tom Hiddleston and Sebastian Stan are just some of the former Avengers stars announced to be returning in the livestream, reprising their roles as Thor, Captain America, Ant-Man, Loki and Winter Soldier, respectively.

Meanwhile, Florence Pugh, David Harbour, Lewis Pullman and Wyatt Russell will be representing Thunderbolts*, while The Fantastic Four’s Pedro Pascal, Vanessa Kirby, Joseph Quinn and Ebon Moss-Bachrach will also be making their Avengers debut in Doomsday.

The biggest shock of them all came when stars from the X-Men films of the early 2000s were revealed to be joining MCU characters in Avengers: Doomsday.

Among them are Patrick Stewart as Charles Xavier, Ian McKellen as Magneto, James Marsden as Cyclops, Alan Cumming as Nightcrawler, Rebecca Romijn as Mystique and even Channing Tatum’s Gambit, who most recently made a cameo in Deadpool & Wolverine, is returning.

Due to legal reasons, the Avengers and X-Men have never been able to share the screen together until recently.

Historically, 20th Century Fox had held the film rights to X-Men, stopping any potential crossovers, but since Disney’s acquisition of Marvel Studios, and then Fox, the two superhero groups can now appear on screen together (as evidenced in last year’s Deadpool & Wolverine).

As Wakanda serves as a major tactical and narrative hub, expect your favourite Black Panther characters to also appear in the upcoming film, too.

Letitia Wright returns as Shuri, AKA the new Black Panther, alongside Winston Duke and Tenoch Huerta as M’Baku and Namor.

Simu Liu will also be back as Shang-Chi, for the first time since 2021′s Shang-Chi And The Legend Of The Ten Rings.

Meanwhile, because no one ever truly stays dead in the MCU, Chris Evans will be returning as Captain America, although the circumstances around his comeback remain shrouded in mystery.

“I said I would only come back if there was a real reason, and in Doomsday, there’s a very real reason why these heroes need Steve Rogers,” Chris Evans revealed at this year’s CinemaCon, with Hayley Atwell also expected to return as Steve’s beloved SHIELD agent Peggy.

And talking of the dead never staying dead in the MCU, Robert Downey Jr. is back, too – only this time, it’s not as Tony Stark…

In July 2024, Marvel fans attending Comic-Con were shocked when Doctor Doom appeared on stage, removing his infamous green cape to reveal himself as Robert Downey Jr.

The new Avengers film’s main antagonist – a genius scientist from the fictional Latveria, who seeks world domination – first made a cameo in the post-credits of last year’s Fantastic Four: First Steps, although at the time, his identity remained hidden behind his iconic mask.

Robert’s last Marvel film was 2019′s Avengers: Endgame, in which his character Tony Stark sacrificed himself to save the world.

In March 2025, the directors of Avengers: Doomsday told Variety that the Oscar winner had been “immersed” in his new character, and was heavily involved in the creative process.

“He’s writing backstory, costume ideas,” Joe Russo said about Robert’s commitment to the franchise. “We were just on the phone with him this morning before we got here talking about it. He just loves really rich three-dimensional characters. He sees a real opportunity here with the character.”

Kevin Feige shared that Robert has been “ingrained in the fabric” of the MCU for so long that they couldn’t help but “talk about when and how and if there could be a return”.

However, when asked how the idea of bringing Robert back as Doom came about, he did tell Entertainment Weekly in April this year that: “It’s our universe. It’s a multiverse. We can do whatever the heck we want. He played the most iconic hero. Let’s have him play the most iconic villain.”

Robert recently spoke to CBR alongside Joe Russo, and revealed that this film “landed in a place that I think will more than suffice” for fans.

“It’s not even about how I executed it,” the Oscar winner actor added. “It’s about the way it’s been structured, and the other characters.

“There’s something going on in Doomsday and forward that is literally the only antidote to: How do you not have these films be let down after an Infinity War and an Endgame? And boy, have we laboured long and hard to bring that down.”

As for why Doom’s face looks so similar to Tony Stark, we’ll have to wait until Avengers: Doomsday is released to find that out…

Jonathan Majors made his debut as Kang The Conqueror in the first season of the Marvel TV series Loki, before playing a key role in the underwhelming Ant-Man And The Wasp: Quantumania.

After the heroes defeated Thanos in Avengers: Endgame, Kang looked set to play the newest big bad, with numerous appearances for Jonathan Majors having been slated.

In fact, Avengers: Doomsday was originally called Avengers: The Kang Dynasty, and was set to revolve around Jonthan’s time-travelling, multiverse-hopping superhuman character.

However, after Jonathan was arrested in 2023 under charges of strangulation, assault and harassment, Marvel was forced to drastically rethink their fifth Avengers film.

Jonathan was eventually found guilty of one count of reckless assault in the third degree, and a charge of harassment as a violation. In April 2024, he was sentenced to 52 weeks of a domestic violence intervention program and probation.

In December 2023, a studio rep confirmed Jonathan wouldn’t return to the franchise, and his role was never recast.

Despite the controversy around Jonathan’s exit from the Marvel universe, studio boss Kevin Feige has always maintained that the pivot from Kang to Doom as a central villain was an entirely creative one.

“We had started even before what had happened to the actor happened, we had started to realise that Kang wasn’t big enough, wasn’t Thanos, and that there was only one character that could be that, because he was that in the comics for decades and decades,” he told The Hollywood Reporter in the summer of last year.

Destin Daniel Cretton, the director of Marvel’s Shang-Chi And The Legend Of The Ten Rings and Wonder Man, was first set to helm the film, back when it was still being referred to as The Kang Dynasty.

In November 2023, Deadline reported that Destin had left the project to pursue other Marvel projects, including the upcoming Spider-Man: Brand New Day.

Taking over from Destin are brothers Anthony and Joe Russo, who previously directed the Captain America films The Winter Soldier and Civil War, as well as the Avengers films Infinity War and Endgame.

Originally, the Russo brothers turned down the chance to direct both Avengers: Doomsday and its sequel, Secret Wars, due to the strain and energy of making such epic blockbusters.

“Robert [Downey Jr] tried to talk us into doing it and we said, ‘No’,” Joe Russo revealed to Omlete last year. “We just didn’t have a story. We didn’t have a way in, right? We were resistant for a while.

“And then one day [Endgame writer] Steve McFeely, who’s one of our key collaborators, said, ‘I have an idea.’ And we went, ’That’s the story. That story has to be told. It’s a really powerful story.”

The brothers have been tight-lipped about the film’s finer details, although they did tease: “We love villains who think they’re the heroes of their own stories. That’s when they become three-dimensional and when they become more interesting.

“And when you have an actor like Robert Downey, you have to create a well-shaped three-dimensional character for the audience.”

Marvel has slowly been releasing teaser trailers for Avengers: Doomsday, each of them themed around a different hero.

At CinemaCon in April, they did release a trailer for the press – and industry pros lost their minds over it.

While it’s still never been made available to the general public, a YouTuber has recreated the trailer shot-for-shot using Lego.

Back in December, an official teaser premiered, depicting Chris Evans’ Steve Rogers in full dad mode, cradling a baby above a crib, hinting that in his alternate universe, he and Peggy got their happy-ever-after ending.

A second trailer saw the X-Men back in comic-appropriate attire, featuring Ian McKellen back as Magneto alongsidde Patrick Stewart’s Professor Charles Xavier and James Marsden as Cyclops.

Following this, a third teaser depicted the return of Chris Hemsworth as Thor, calling on his father Odin to help in the upcoming war.

The most recent trailer brought us a crossover between Wakanda and the Fantastic Four, with the short clip featuring Ben Grimm, AKA The Thing, introducing himself to the Wakanadans.

Avengers: Doomsday is officially scheduled to release in cinemas on 18 December 2026.

If this date sounds familiar, that’s because it is also when Dune: Part Three is also scheduled to hit cinemas.

This has already caused upset among fans and cinema owners, who have voiced their concerns that the clash could cause audiences to pick just one film to see on opening night, as well as limiting IMAX screenings.

An Avengers: Doomsday sequel, Avengers: Secret Wars, will hit cinemas almost a year to the day later, on 17 December 2027.

If you can’t wait until then, Spider-Man: Brand New Day swings into cinemas on 31 July 2026 – and promises to introduce plot points and characters from the upcoming Doomsday movie.