Spider-Man: Brand New Day has added two more high-profile cast members — Sadie Sink (Stranger Things' Max Mayfield) and Liza Colón-Zayas (The Bear's Tina Marrero) — in roles Marvel Studios is refusing to confirm. The casting reveals dropped overnight; theory threads are already at thousands of comments.
Marvel Studios confirmed Sadie Sink and Liza Colón-Zayas to the Spider-Man: Brand New Day cast in a brief Disney social-media post yesterday afternoon. Neither character is named. No images. No production stills. Just two names added to a cast list that already includes Tom Holland, Charlie Cox, Zendaya, and Jacob Batalon.
The fan theories are running hot. The most-popular Sadie Sink theory: she's playing Jean Grey — a teenage Phoenix-arc setup ahead of the eventual MCU X-Men reboot. The theory traces back to a 2024 fan-art campaign that mocked-up Sink as Phoenix; the campaign trended for weeks. Sink's age (24), her redhead casting, and her dramatic-acting credentials all fit. Marvel has not denied or confirmed.
The second-most-popular Sink theory: she's playing Mary Jane Watson's older sister — a setup for the inevitable Spider-Man reboot's Sandman-adjacent storyline. The theory is less viral but more script-credible — the film's screenwriters Chris McKenna and Erik Sommers wrote heavily-altered family-relationship dialogue during 2025 reshoots.
Liza Colón-Zayas's role is more constrained by theory. The Bear's Emmy-winning actress is, at age 53, an unusual choice for a comic-book film. Most fan theories center on Aunt May–replacement roles (Aunt May died in No Way Home (2021)). The most-credible theory: she's playing Lt. Yuri Watanabe, a Marvel Comics police character recently used in the PlayStation Spider-Man games. The character would integrate cleanly with Charlie Cox's Daredevil arc.
The strategic context: Marvel has been adding cast members to Brand New Day at an unusual rate for the past four months — six confirmed additions since January, including Cox's Daredevil and Vanessa Kirby (rumored Madame Web cameo). The film's marketing strategy appears to be slow-drip casting reveals designed to maintain attention through the July 31, 2026 release window.
For broader context, see our Brand New Day hub, our final-trailer coverage, and our Daredevil casting analysis.