Sadie Sink’s entry into the Marvel Cinematic Universe is far more expansive than a one-off appearance. Beyond her debut in Spider-Man: Brand New Day, it has been confirmed that she will play a pivotal role in Avengers: Secret Wars. This multi-film contract positions her as a cornerstone of the MCU’s Phase 6 and the upcoming Mutant Saga, with her character rumored to be the catalyst for major multiversal shifts
Max Mayfield Just Became Jean Grey and She Is Staying for a While
Jeff Sneider confirmed on The Hot Mic what the fandom had been speculating for over a year. Sink is playing Jean Grey. Marvel has not officially confirmed it, but Sneider put his name on it, and scooper Cryptic HD QUALITY followed up with character details the same day. Jean’s powers have a new visual flair compared to previous versions.
More VFX is involved. The look is described as resembling her X-97 comics counterpart. Cryptic also said she is “time displaced,” meaning she may be from the past or an alternate universe. Nothing confirmed officially yet.
The contract itself is what makes this a bigger story than just the casting. Deadline reported she is locked for Secret Wars, too. That is Spider-Man: Brand New Day on July 31, 2026, then Avengers: Secret Wars on December 17, 2027.
Two films minimum. The X-Men reboot, directed by Jake Schreier, is also in development for a rumored 2028 release, which means Jean Grey is being built as a long-term MCU character, and Sink is the face of that.
Sink said keeping the secret has been “torture.” “I feel like keeping Stranger Things secrets are kind of easy because I have so many Spider-Man secrets I’m sitting on that feel even more secretive,” she told The Hollywood Reporter. She found out about the Marvel casting while wrapping Stranger Things Season 5 in 2024.
The timing worked out because of Romeo and Juliet. Sink is doing her London West End debut opposite Noah Jupe in the first few months of 2026. Secret Wars starts filming in London later that year. She stays in the same city and moves from the stage to an Avengers set. That is a schedule that basically wrote itself.
The X-Men reboot is being written by Michael Lesslie, who did Hunger Games: Ballad of Songbirds and Snakes. Jack Champion is rumored for Cyclops, Julia Butters for Kitty Pryde, and Margaret Qualley for Rogue. None of it has been confirmed. Sink is the only one with actual contract confirmation.
From Stranger Things to Jean Grey to the X-Men reboot. The pipeline is set. Brand New Day is four months out, and the Jean Grey reveal is coming whether Marvel announces it or not.
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New reports hint at Sadie Sink’s role in ‘Spider-Man: Brand New Day’
