Sadie Sink, one of Hollywood’s brightest young stars, is officially joining the Marvel Cinematic Universe (MCU), sparking massive speculation about her role in the upcoming Avengers: Secret Wars. After captivating audiences as Max Mayfield in Netflix’s Stranger Things and proving her acting prowess in films such as The Whale and O’Dessa, Sink is now stepping into a major franchise spotlight. Although her exact character remains a well-guarded secret by Marvel, fans and experts alike are buzzing with theories about who she might be portraying.
Sadie Sink’s Entry into the MCU
Following her acclaimed performances that garnered her a Tony nomination for Best Actress in a Play for John Proctor is the Villain in 2025, Sadie Sink is poised for a significant career leap. Her casting in Avengers: Secret Wars, scheduled for release in December 2027, hints at a substantial role within the MCU’s expansive narrative. Intriguingly, Sink is also set to appear in the 2026 MCU film Spider-Man: Brand New Day, yet Marvel remains tight-lipped about her character.
The Leading Theory: Jean Grey
Jean Grey is currently the most popular and convincing theory surrounding Sadie Sink’s role. As Marvel steadily integrates the mutant saga into the MCU, introducing Jean Grey aligns with the studio’s long-term plans to bring X-Men into the fold. Jean Grey, renowned as one of Marvel’s most powerful mutants, possesses advanced telekinetic and telepathic abilities. Her transformation into the Phoenix marks her as a near-unstoppable force.
Sadle Sink’s youthful energy and iconic red hair make her an excellent fit to carry forward Jean Grey’s legacy, previously portrayed by Famke Janssen and Sophie Turner. However, the puzzling aspect of this theory is Sink’s debut in a Spider-Man film, which might suggest a character tied more closely to the Spider-Man universe initially. Yet, her casting in Secret Wars potentially sets the stage for the MCU’s long-awaited introduction of the X-Men universe.
Spider-Man Universe Connections: Gwen Stacy and Mary Jane Watson
Given her role in Spider-Man: Brand New Day, some fans speculate Sink could be portraying a significant character from Spider-Man lore, such as Gwen Stacy or Mary Jane Watson.
Gwen Stacy has evolved from a traditional love interest to a heroic figure in the Spider-Verse animated films, fighting villains alongside Miles Morales. Introducing Gwen as a love interest with her own superpowers could deeply enrich Peter Parker’s storyline, especially as Zendaya’s MJ appears disconnected from him in the current MCU arc. Despite set photos showing Sink without Gwen’s signature blonde hair, Marvel’s secrecy could mean the look is being purposefully concealed.
Alternatively, Sink might take on an alternate universe version of Mary Jane Watson. Although Tom Holland’s Peter Parker and Zendaya’s MJ are on a hiatus, the multiverse opens the door for other versions of iconic characters. Sink’s Mary Jane might not replace Zendaya’s but could appear to challenge Peter or remind him of the importance of connection and partnership.
Other Possible Roles: Mayday Parker, Carlie Cooper, and Rachel Cole-Alves
Another compelling idea is that Sadie Sink could be playing Mayday Parker, the daughter of Peter Parker and Mary Jane Watson in certain Spider-Man comic continuities. Mayday’s inclusion would deepen the multiverse narrative and connect the legacies of previous Spider-Man franchises. With Tobey Maguire’s Peter already reintroduced, it would be a natural progression to show his family’s next generation.
There’s also speculation around Carlie Cooper, a lesser-known but vital character in the “Brand New Day” comic arc. Carlie, a dedicated NYPD officer, investigates corruption and eventually dates Peter Parker. Her storyline could intertwine with darker Marvel narratives, including the Punisher’s appearances, expanding the MCU’s street-level hero scope.
Lastly, some consider the possibility of Sink playing Rachel Cole-Alves, a former Marine sergeant who partners with the Punisher. However, this theory seems less likely given the current plans for a dedicated Punisher special, and Sink’s early involvement in a major event like Secret Wars suggests a more prominent character.
Avengers: Secret Wars and MCU Future
Avengers: Secret Wars, directed by the Russo brothers and produced by Kevin Feige, is set for a December 17, 2027 release date. The film is highly anticipated as it promises to be a pivotal moment in the MCU, weaving together multiple story threads, including the introduction of key X-Men characters and deepening the Spider-Man multiverse. Sadie Sink’s involvement confirms her as a crucial new player in this evolving universe, though Marvel continues to keep her role tightly under wraps.
Conclusion
Sadie Sink’s casting in Avengers: Secret Wars has sparked intense speculation about her character, with the strongest theories centering on iconic figures like Jean Grey, Gwen Stacy, Mary Jane Watson, or even Mayday Parker. Whatever role she ultimately inhabits, it’s clear that her inclusion signals exciting new directions for the MCU, especially as it embraces the mutant saga and the Spider-Man multiverse. Her talent and rising star power make Sink a perfect addition to Marvel’s grand narrative. Share your thoughts in the comments and explore more at keeperfacts.com.
