Sadie Sink’s mystery MCU role reportedly continues into Avengers: Secret Wars

A new report indicates that Sadie Sink’s undisclosed role in Spider-Man: Brand New Day may extend into Avengers: Secret Wars, potentially signaling a larger presence for the Stranger Things star in the Marvel Cinematic Universe. According to Deadline, Sink—who is set to appear in the upcoming Spider-Man film—will reprise the same character in Secret Wars, scheduled for release in December 2027. io9 noted that Marvel Studios did not comment when contacted about the report.

The development is noteworthy because Sink’s character in Brand New Day has remained completely under wraps despite months of speculation and production nearing completion. If her role carries over into Secret Wars, it may suggest that the character plays a more significant narrative function than previously assumed.

Fans have floated several possibilities, particularly with Secret Wars marking the conclusion of the MCU’s Multiverse Saga. One theory is that Sink could portray a character whose importance shifts across different universes—someone ordinary in Brand New Day but a hero in Secret Wars, or a new hero whose arc expands across both films. Another, more grounded scenario is that she appears as the same non-hero or hero character in both movies to support broader storylines.

With limited information available about Brand New Day, Avengers: Doomsday, and Secret Wars, details remain speculative. Sink will first appear in Spider-Man: Brand New Day on July 31, 2026, followed by Avengers: Doomsday on December 18, 2026, before Secret Wars arrives the following year.