Avengers: Doomsday opens December 18, 2026 — its second release date change, after the film was bumped from an earlier May 1, 2026 slot. The first full trailer has already dropped, confirming the December date is still on track.
The actual plot is still under wraps, but Robert Downey Jr. is returning to the franchise not as Iron Man but as the villain, Doctor Doom, and Marvel has confirmed him as the film's main antagonist, with the Fantastic Four pulled into the story and the Russo Brothers back directing. Teasers also show Thor, the X-Men, and Wakandan characters joining the fight alongside a returning Captain America/Steve Rogers, and the story reportedly ties into the events of Thunderbolts* and The Fantastic Four: First Steps.
It's set up as the first half of a two-part saga that wraps with Avengers: Secret Wars in 2027 — beyond that, the actual story beats are still a closely guarded secret.