Sadie Sink at the Los Angeles premiere of "Spider-Man: Brand New Day." WireImageWarning: Spoilers ahead for Spider-Man: Brand New Day. Spider-Man: Brand New Day is now in theaters, and fans finally have a long-awaited answer to one of the biggest pre-release questions: Who is Sadie Sink playing in the film? Sadie Sink Plays Jean Grey In ‘Spider-Man: Brand New Day’ Sadie Sink as Jean Grey in "Spider-Man: Brand New Day." For a chunk of Brand New Day, Jean is believed to be the villain.