After her confirmed casting in Spider-Man: Brand New Day, Stranger Things star Sadie Sink is reportedly set to join the massive ensemble cast of the next confirmed Avengers film, Avengers: Secret Wars, following her entry into the Marvel Cinematic Universe. This news signals a major, long-term role for the actress within the franchise.
Although her role has not yet been disclosed, Sink will make her MCU debut in Spider-Man: Brand New Day, which is scheduled to hit the theatres on July 31, 2026. As of now, the actress is set to appear in the final season of Netflix's Stranger Things, which will release with the first four episodes on Nov. 26
The highly anticipated Spider-Man: Brand New Day is helmed by Shang-Chi director Destin Daniel Cretton. The film features a major ensemble cast, including returning stars Tom Holland (Spider-Man), Zendaya, and Jacob Batalon, alongside notable new additions such as Jon Bernthal (The Punisher) and Mark Ruffalo (The Hulk).
A central mystery remains the role of Sadie Sink. Her character is currently unknown, but due to her confirmed casting in the future Avengers: Secret Wars, speculation is intense, and has sparked several fan theories on the internet.
Given that the Russo brothers' upcoming Avengers film is expected to unite the Avengers with the X-Men and various other superheroes, many observers are convinced that Sink will portray an iconic character from the Mutants' roster. While many details of Spider-Man: Brand New Day and Avengers: Secret Wars are still awaited, Sink is set to appear in the final season of Netflix's Stranger Things.
The American actress debuted in the second season of the series as Maxine "Max" Mayfield, who moved to Hawkins with her stepbrother Billy (Dacre Montgomery). In Stranger Things season 4, Max became Vecna's primary target, spending the season fighting the villain and her own inner demons stemming from grief.
Her fate remains a mystery after the conclusion of season 4. Vecna managed to break her limbs and blind her, leading to her clinical death for a short period. Eleven intervened, using her powers to revive Max, but could not reverse the physical damage. Max was last seen in a coma in the hospital, with the Duffer Brothers confirming her condition as "brain dead."
While we are yet to see what happens to her character in the final season, Sink recently featured as the lead in the post-apocalyptic musical drama film O'Dessa, which was released earlier this year.