Musician Steve Lacy revealed that Sadie Sink plays Jean Grey in Spider-Man: Brand New Day during a red carpet interview at the film's Los Angeles world premiere on Monday, 28 July 2026 — apparently before most of the audience had seen the film.

Lacy, whose song from his third studio album Oh Yeah? features as the title track for the Marvel sequel, was speaking to streamer Valkyrae on the premiere's official livestream when he named Jean Grey as his favourite character in the film Forbes. The remark confirmed what Marvel had otherwise kept under wraps: that Sink, known for Stranger Things, would be playing the iconic X-Men mutant Complex; The Independent.

Director Destin Daniel Cretton told Rolling Stone that there was a narrative reason the identity of Sink's character had been kept secret Rolling Stone. What that reason is, he did not say — leaving the spoiler's full significance to be weighed by anyone who has not yet caught the film.

Rolling Stone first reported the slip, noting that it occurred during the official livestream of the premiere — meaning the reveal went out to viewers watching from home in real time Rolling Stone. Cretton also directs the film, which takes its subtitle from a 2008 Marvel Comics storyline.

Sink's casting had been announced without a character name attached, which is standard practice for Marvel productions looking to preserve plot details through a film's promotional cycle. Lacy's offhand enthusiasm short-circuited that strategy in seconds.

The moment landed at the intersection of two entertainment worlds: Lacy is a Grammy-nominated artist whose involvement with the film extends to its music, not its cast — and yet his red carpet appearance put him in a position to break a secret the studio had carefully maintained.