For months, Marvel fans wondered who Sadie Sink would play in Spider-Man: Brand New Day. Now, the mystery is over.
The Stranger Things star has officially entered the Marvel Cinematic Universe as Jean Grey, one of the most powerful and significant mutants in comic book history.
According to ScreenRant, Marvel revealed the role after Spider-Man: Brand New Day began its theatrical run, ending months of speculation.
Sink joined the cast in March 2025, but the studio kept her character secret throughout production and promotion. The actress also repeatedly avoided confirming the Jean Grey rumours.
Her casting carries major importance for Marvel’s future.
In the comics, Jean Grey is a founding member of the X-Men and one of Marvel’s most complex characters, with stories centred on identity, power and control.
She is also the host of the Phoenix Force, a cosmic entity that gives her extraordinary abilities while creating one of the X-Men’s most tragic storylines.
In Spider-Man: Brand New Day, Marvel introduces a younger Jean as a mysterious hooded figure with telepathic powers.
She can move between people’s minds and initially appears to be an antagonist. However, the film reveals that her actions are connected to her search for her sister, Sara Grey.
Jean’s arrival hints at Marvel’s upcoming X-Men era. The studio appears to be taking a younger approach to mutants, following Marvel Studios president Kevin Feige’s comments about a “reset” after Avengers: Secret Wars rather than a traditional reboot.
ScreenRant’s review praised Sink’s introduction, with critic Graeme Guttman noting that Jean’s mind-based abilities add a deeper look into Peter Parker’s emotional struggles.
The biggest question now is Jean’s future. Reports have linked Sink to Avengers: Secret Wars, although Marvel has not confirmed her appearance. If Marvel follows the comics, Jean could become a major figure in the next generation of X-Men stories.
Spider-Man: Brand New Day may only be the beginning of Sadie Sink’s mutant journey.
