The star-studded Marvel film acts as an epic sequel to 2019's Avengers: Endgame.10:14, 21 Jul 2026Avengers: Doomsday's new trailer is packed full of jaw-dropping reveals.‌Marvel fans are gearing up for the release of the 39th film in the Marvel Cinematic Universe (MCU) after the epic trailer was released.‌Avengers: Doomsday is coming to UK cinemas on December 18 and it brings together the Avengers, Wakandans, New Avengers, Fantastic Four, and the X-Men to face one enemy - Doctor Doom.‌The true identity of Doctor Doom was previously unveiled to be none other than Iron Man's Robert Downey Jr.The film's trailer shows Thor (Chris Hemsworth) bring together heroes from across the MCU as he warns them: "I have fought with many warriors in my time, who are far stronger than all of us put together."And they died. They died facing enemies and threats that scared me far less than this one." Here is all you need to know about how the trailer introduces Doctor Doom amongst other new faces.‌Did Tony Stark become Dr Doom?Following some epic battle scenes, Thor is seen using his hammer in an attempt to take down Doom, who appears to push him away with ease.‌He appears to warn: “Something’s coming, something we may not be able to deter. Before this day is done, we shall be faced with an unthinkable decision.”Downey Jr revealed his villain role back in 2024 and it caused widespread confusion amongst fans as they wondered how the actor's Iron Man character could become Doctor Doom.An evil but brilliant scientist and sorcerer with a trademark metal mask that hides his scarred face, the character is best known as the nemesis of the Fantastic Four.‌Tony Stark never became Doctor Doom in the Marvel comics, so fans have been wondering how this casting will be explained on screen, with some believing the character may never take his mask off to reveal his true identity to the other characters.Directors Anthony and Joe Russo said Doom was one of the most complex comic book characters, and they thought Downey Jr was the one person who could take on the role.‌Russo told San Diego Comic Con: "If we’re going to bring Victor Von Doom to the screen — he is one of the more complex characters in all of comics … this is potentially one of the more entertaining characters in all of fiction. If we’re going to do this … then we are going to need the greatest actor in the world.”Who plays Mystique in Avengers: Doomsday?‌The trailer also unveils the Mystique actress as Florence Pugh's Yelena Belova is seen taking her on in a fight.Mystique is played by Rebecca Romjin, a 53-year-old American actress also known for her role as Una Chin-Riley in the Star Trek universe.The former model played Mystique in the 2000 X-Men as well as in X2, X-Men: The Last Stand and X Men: First Class.‌In 2025 the star spoke to PTI about the "unexpected" and "surreal" moment she found out she would be returning after Jennifer Lawrence took over the role.She expanded: "I want to be proud of the work that I get to come back and show [her children]… especially within the ‘Star Trek’ and genres of science fiction and comic books."I really enjoy playing female characters that are multifaceted and often just as strong as the male characters. It’s important to me.”‌Captain America's epic returnTowards the end of the trailer, a mysterious voice is heard saying: "Hey, pal," to Thor, who is seen looking stunned.‌"It's not possible," he says, before Thor hands him his hammer, which the figure easily accepts.With longer hair and a beard, the figure is revealed to be Chris Evans' Captain America, who had travelled back in time to live a happy life with Peggy Carter (Hayley Atwell).He returned to the main timeline as an elderly man and officially retired from his superhero role, yet in the new trailer, he is back to his younger self.Article continues belowFans took to the YouTube comments to share their thoughts on Steve Rogers' return, with one saying: "Hammer guy Steve is here."Another said: "Welcome back Steve Rogers," to which a third fan responded: "Yes it got me there. Can't wait."Avengers: Doomsday is coming to cinemas on December 18