Sadie Sink’s surprising Spider-Man 4 casting announcement supports my theory that the Stranger Things star is playing the X-Men hero Jean Grey in the MCU. The MCU’s Spider-Man 4 is advancing in development faster than other MCU sequels, and a lot may be at stake, both for Tom Holland’s Spider-Man journey and the MCU as a whole. Given that the chances of Zendaya’s MJ and Jacob Batalon’s Ned Leeds returning for the MCU’s next Spider-Man movie are low after Spider-Man: No Way Home‘s ending, it’s likely that Holland’s Peter Parker will be joined by new friends in Spider-Man 4.

Spider-Man 4‘s plot details remain under wraps, and the biggest questions surrounding Spider-Man’s next solo movie involve the film’s tone, Peter Parker’s supporting cast, and the potential allies Spider-Man might team up with. Candidates for Spider-Man’s teammate include Daredevil, Ant-Man, Shang-Chi, and any mutant already present in the MCU multiverse, like ᴅᴇᴀᴅpool or Wolverine. However, Marvel Studios could make a bold move in Spider-Man 4 and introduce a new MCU hero who could make their debut at the end of the Multiverse Saga at the same time that Peter Parker restarts his life from scratch.

Sadie Sink Has Been Cast In Spider-Man And Speculation Points To Her Playing Jean Grey

Sadie Sink Is The First Big Name To Join The MCU For Spider-Man 4

On March 12, 2025, ᴅᴇᴀᴅline reports that Sadie Sink has joined Spider-Man 4‘s cast. Before Sink’s official casting was reported, it was heavily speculated that she would be playing a major MCU character soon, with the most popular theories revolving around the X-Men member Jean Grey. While these used to be fan theories, Sadie Sink’s Spider-Man 4 casting suggests that they may have had a solid basis all along. Sadie Sink played Max Mayfield in Stranger Things, who bears some similarities to Marvel’s Jean Grey a.k.a. Phoenix.

If Sadie Sink Plays The MCU’s Jean Grey, It Fulfills My Ultimate Dream Casting

Stranger Things Proved Sadie Sink Would Be An Amazing Jean Grey In The MCU

In Stranger Things, Sadie Sink’s Max death opens the last curse gate that allows the dark enтιтy Vecna to expand his reach outside the Upside Down realm. However, Eleven brings Max back to life, even though it seemed impossible for Max to survive the ordeal. Max Mayfield’s sacrifice in Stranger Things is quite similar to Jean Grey’s Phoenix Force dynamics. In Marvel Comics and Fox’s X-Men movies, Jean Grey is destined to sacrifice herself to both unleash the Phoenix Force upon the world and stop it, always coming back to life one way or another.

Sadie Sink’s Stranger Things role has made her a coveted actor, and at twenty-two years old, she’s young enough to enter a movie franchise as expansive as the MCU as a recurring character and still have plenty of time to move on to other projects afterward. At around twenty-five years old, Sadie Sink’s Jean Grey could become one of the main stars of the MCU’s Mutant Saga after Phase 6 ends. Other big-name actors around Sadie Sink’s age could join her for the MCU’s first X-Men movie and other mutant-related projects.