Spider-Man 4 Has Cast Stranger Things' Sadie Sink As Its First New Actor, And There's Already A Wild Theory On Who She's Playing

It’s been a minute since we hung out with Tom Holland’s Peter Parker in Spider-Man: No Way Home, but development on the 2026 release of Spider-Man 4 is chugging along nicely. Today is an especially big day for the upcoming Marvel movie, as it’s been revealed that Stranger Things’ Sadie Sink is the first new actor to be cast in it. Not only that, there’s already a wild theory about who she’ll play in the Web-Slinger’s next cinematic adventure.

We have Deadline to thank for this casting update, which comes ahead of Spider-Man 4 expected to begin production sometime this summer. Now, since this is a Marvel Studios project (in collaboration with Sony Pictures, of course), details on who Sink is playing are understandably being kept secret for now. However, as noted in the article, there’s already been a theory going around for months that the Max Mayfield actress will be the Marvel Cinematic Universe’s Jean Grey.

Granted, the article also mentions it’s possible that Saide Sink could be playing “another beloved redheaded Spider-Man character,” meaning Mary Jane Watson. However, since we already got an “MJ” through Zendaya’s Michelle Jones-Watson in the first three Tom Holland-led Spidey movies, I have my doubts about this possibility. Either way, Sink’s role will be “significant” and follow on the heels of Stranger Things Season 5 wrapping up the sci-fi/horror saga set in 1980s Hawkins, Indiana at a yet-to-be-announced date on the 2025 TV schedule.

Previously played by Famke Janssen and Sophie Turner in the X-Men movies from the 20th Century Fox era, Jean Grey is one of Marvel’s most well-known mutant superheroes. With the MCU peppering in X-Men references for several years now and an X-Men reboot movie on the way, it stands to reason that we’d get a new version of the telekinetic and telepathic superhero rather than just leave her on the sidelines. That’s been strengthened by the rumors that have been going around for months that Sadie Sink is the “frontrunner” to play Jean.

While having Jean Grey make her MCU debut in an upcoming Spider-Man movie might sound unusual at first, it’s actually pretty par for the course. Among the things Tom Holland’s Spider-Man movies are best known for are including major Marvel characters who aren’t directly part of Peter Parker’s supporting cast in the comics. Tony Stark/Iron Man and Happy Hogan appeared in Homecoming, Nick Fury and Maria Hill appeared in Far From Home, and Doctor Strange appeared in No Way Home.

Assuming Sadie Sink is indeed playing Jean Grey, the question then becomes how will she cross paths with Peter in Spider-Man 4? At the end of Spider-Man: No Way Home, Doctor Strange erased everyone’s memory of Peter in order to save the Marvel multiverse. So now our intrepid wall-crawler is on his own and forging a new life for himself, one without MJ and Ned. It’s easy enough to envision Peter somehow meeting Jean, and presumably she already has her powers, though I’m skeptical about if she’s already affiliated with the X-Men.

Once there’s official word on Sink’s involvement in Spider-Man 4, as well as whom she’ll play, we’ll pass that information along. For now, I’m just looking forward to the actress sharing screen time with Tom Holland and the mere possibility that Jean Grey will be present in this movie opening on July 31, 2026.