Leaked ‘Avengers: Doomsday’ teaser signals X-Men’s MCU debut

A third teaser for "Avengers: Doomsday" has leaked online, offering the clearest indication yet that the X-Men are officially entering the Marvel Cinematic Universe (MCU). The leaked footage places Patrick Stewart and Ian McKellen at the centre of the reveal, reprising their iconic roles as Professor Charles Xavier and Magneto.

The teaser is the latest in a string of leaks surrounding the film. Earlier, short promos hinting at the returns of Chris Evans and Chris Hemsworth had circulated online. This new footage, however, shifts focus to the long-anticipated arrival of the X-Men within the MCU.

Shared widely on social media late Sunday, the teaser appears to have been recorded on a mobile phone inside a cinema. It opens with images of the Xavier School for Mutants engulfed in flames, accompanied by a voice-over from Stewart's Professor X reflecting on survival amid the conflict. The footage then shows an interaction between Professor X and McKellen's Magneto, followed by a brief shot of Sentinels causing destruction.

One of the most discussed moments features Cyclops, who is seen unleashing a powerful optic blast — a scene that has quickly become a focal point of online discussion.

Although the original clip was low in quality, by Monday several social media accounts had uploaded AI-enhanced versions, presenting clearer footage and high-resolution stills from the teaser.

Fans have responded enthusiastically, with many calling the leaked teaser more compelling than the earlier promos teasing Steve Rogers and Thor. The Cyclops sequence, in particular, has drawn praise, with some viewers describing it as more impactful than previous portrayals of the character in films produced by 20th Century Fox, which held the X-Men film rights before Disney's acquisition.

"Avengers: Doomsday" is positioned as a major crossover event for the MCU. Robert Downey Jr is set to return in a new role as the villain Doctor Doom. The ensemble cast also includes Anthony Mackie, Danny Ramirez, Sebastian Stan, Paul Rudd, Tom Hiddleston, Letitia Wright, Winston Duke, Simu Liu, Pedro Pascal, Vanessa Kirby, Joseph Quinn, Ebon Moss-Bachrach, Florence Pugh, David Harbour, Wyatt Russell, Hannah John-Kamen and Lewis Pullman.

The film is scheduled for a worldwide release in December 2026.