Stranger Things' Sadie Sink to star in Avengers: Doomsday? Report

Avengers: Doomsday has already had one release date shift, moving from May 1, 2026, to its current December slot.

Sadie Sink’s career is moving with the kind of momentum most actors only dream about, and the latest development pushes her firmly into Hollywood’s biggest league. According to a fresh report from Deadline, the 23-year-old talent is set to join the cast of Avengers: Doomsday, one of Marvel’s most anticipated upcoming films.

The project is slated to release on December 18, 2026, as part of MCU’s Phase Six, marking yet another major franchise for the actress who has already impressed audiences in Stranger Things and is gearing up for Spider-Man: Brand New Day.

Here’s the thing: Sink isn’t just dipping her toes into blockbuster territory, she’s fully stepping in. Deadline shared insights during a conversation with producer James Bierman, noting that while the exact nature of her role in Spider-Man: Brand New Day is still under wraps, her participation in the next Avengers film is “known” and nearly set. Filming for Doomsday is expected to kick off in London later in 2026, and this aligns neatly with her current schedule.

Right now, Sink is juggling a packed slate. She is in the middle of a global promotional run for Stranger Things Season 5, where she reprises her fan-favourite role as Max Mayfield.

Once her promotional duties wrap, she’ll continue filming Spider-Man: Brand New Day until mid-December. The Tom Holland-led film is slated for a July 31 release and has generated plenty of speculation about Sink’s mystery character. Even insiders admit they don’t know the specifics yet, but the buzz around her involvement has only grown.

Avengers: Doomsday has already had one release date shift, moving from May 1, 2026, to its current December slot. With Robert Downey Jr. returning and the MCU reshaping itself for its next chapter, expectations around the film are sky-high. Sink’s addition signals Marvel’s intent to bring in younger performers who can carry the franchise into its next decade.

Also read: Robert Downey Jr. makes villainous debut as Doctor Doom in Avengers: Doomsday promo reveal

What makes Sink’s trajectory even more interesting is that she’s balancing franchise work with her theatre roots. She has officially signed on to play Juliet in Robert Icke’s new staging of Romeo & Juliet, with Noah Jupe set to star opposite her as Romeo. It marks a return to the stage for Sink, who began her career in theatre before her breakout on television.

Sadie Sink now stands at a crossroads where blockbuster cinema, prestige theatre, and beloved TV storytelling intersect. With Avengers: Doomsday likely to elevate her into global mainstream stardom, her next chapter looks bigger, bolder, and more unpredictable than ever.