The highly-anticipated MCU sequel Spider-Man 4 is slowly building out its cast ahead of its summer 2026 release. Stranger Things star Sadie Sink is the latest actor to join the Tom Holland-led franchise, and her casting has been the center of countless rumors within the fanbase. Her character in Destin Daniel Cretton's new movie has yet to be revealed, but that hasn't stopped fans from convincing themselves that she'll be playing an Omega Level mutant. With the X-Men officially owned by Disney and a part of the MCU, most of the fandom is convinced that Sink will be the MCU's Jean Grey, a.k.a. the Dark Phoenix. However, the actress is shutting down those rumors.