On March 18, Marvel released the first trailer for Spider-Man: Brand New Day. Within 24 hours, it had racked up 718.7 million views — breaking the record previously held by Deadpool & Wolverine to become the most-watched movie trailer on its debut day in history. Within four days, views surpassed one billion, making it the first trailer ever to cross that threshold. The second trailer arrived on June 17 and went on to become the second most-viewed movie trailer of all time. Between the two, audiences saw Spider-Man, the Punisher, the Hulk, and MJ's new boyfriend — but there was one person whose face you could barely make out. Sadie Sink's name appears in the official cast list. The character column is blank. This is virtually unprecedented in MCU promotional history. Marvel has kept secrets before, but withholding a character's name entirely for over a year is something close to unheard of. That blank space has become the biggest mystery surrounding Brand New Day.
A Quick Primer on Brand New Day
Spider-Man: Brand New Day opens July 31, and is Tom Holland's fourth solo Spider-Man film.At the end of No Way Home (2021), in order to repair a fractured multiverse, Peter Parker asked Doctor Strange to cast a spell that would make the entire world forget he existed — not just forget he was Spider-Man, but erase all the memory of Peter Parker as a person, including those closest to him: his girlfriend MJ and his best friend Ned.Brand New Day begins four years later. Peter is a nameless, forgotten adult living alone in an apartment, protecting New York full-time as Spider-Man. Meanwhile, MJ and Ned are at MIT, and MJ has a new boyfriend, played by Eman Esfandi. Peter knows all of this, and can only watch from afar. As the official synopsis puts it: "The world may have forgotten Peter Parker, but he hasn't forgotten them."Sadie Sink's casting is a story in itself. In March 2025, she revealed on The Tonight Show that she first found out she might be in the film the same way fans did — through online speculation. Deadline subsequently confirmed she had joined the cast in a "significant role," though the character's name has never been officially disclosed. Even more intriguing: Deadline later confirmed that Sink's role won't end with this film. She is set to appear in next year's Avengers: Secret Wars, suggesting that whoever she's playing carries far more weight in the broader MCU than a supporting Spider-Man character typically would.This film's position in the MCU timeline makes that all the more significant. Avengers: Doomsday, arriving this December, is the culmination of Marvel's entire Multiverse Saga — and Brand New Day will be the last MCU film to release before it. With the word "mutant" appearing with growing frequency across the MCU, this film's ending may lay the most critical groundwork for December. Sadie Sink's character could be the thread connecting the Spider-Man universe to that much larger picture.
Who Is Sadie Sink?
If the name doesn't immediately ring a bell, chances are you've already seen her most famous moment.In 2017, at just fifteen years old, she joined Stranger Things Season 2 as Max Mayfield — a skateboarding, Walkman-wearing transfer student who was all sharp edges on the outside but quietly, deeply feeling on the inside. In Season 4 in 2022, Max's escape from the villain Vecna set to "Running Up That Hill" moved countless viewers to tears in front of their screens.Looking across these roles, audiences will find that Sink has a particular gift for characters who appear sharp-edged and guarded at first glance, but carry within them a quiet depth and a powerful, coiled intensity waiting to break through. That quality maps precisely onto the defining traits of several key Marvel characters — which is exactly why, when Deadline announced in March 2025 that she had joined Brand New Day in a "significant role," fan communities didn't stop to ask whether she could handle it. They went straight to asking: who is she playing?
The Leading Theories
Theory A: A Punisher-adjacent character
A figure resembling Sink briefly appears in the background of scenes involving the Punisher. If this turns out to be the answer, Marvel's year-long silence would feel somewhat disproportionate to the reveal — though Marvel has done exactly this before (Mads Mikkelsen's role in Doctor Strange was kept under wraps until release).
Theory B: Mayday Parker
In the comics, Mayday Parker is Peter and MJ's daughter from an alternate universe, with spider-powers of her own. The multiverse framework makes this plausible, and Sink's age roughly fits. The complication is that this is a high-concept premise that would require significant setup for general audiences, and neither trailer contains any visible multiverse thread pointing in her direction.
Theory C: Gwen Stacy
Peter's first love in the comics, and one of the most iconic figures in Spider-Man's history. A Peter with no memory of his past life, encountering a woman who feels inexplicably familiar — the emotional logic is clean and self-contained. Sink's look and demeanor fit the classic Gwen Stacy image closely. The open question is whether a live-action Gwen Stacy might feel like a complication, given how deeply Spider-Man: Into the Spider-Verse has already embedded "Spider-Gwen" in the popular imagination.
Theory D: Jean Grey (X-Men)
If Sadie Sink is playing Jean Grey, it means mutants are formally entering the MCU — not as an easter egg, but as a structural shift in the main continuity. The trailers contain imagery widely read as suggesting telepathic or psychokinetic abilities. Marvel has been building towards an X-Men integration for some time. And Jean Grey's defining characteristic — an immense inner power, suppressed and threatening to break free — aligns closely with the precise quality Sink has demonstrated she can embody. If this is the answer, Brand New Day becomes something considerably larger than a Spider-Man sequel: the opening of an entirely new chapter in the MCU.
