Adam Driver is officially stepping into the X-Men universe — as Mister Sinister. The casting, confirmed by Screen Rant, marks the character’s live-action debut in the Marvel Cinematic Universe, with Driver playing the villain under the alias Nathaniel Millbury. The film, still untitled, is set to hit theaters on May 5, 2028, directed by Jake Schreier and written by Joanna Calo and Lee Sung Jin. It will be the first MCU entry to feature a full reboot of the X-Men franchise, following years of stalled plans and studio shifts. So what happened to Jon Hamm? He was once set to play Sinister in The New Mutants, back when 20th Century Fox still held the rights. That version never materialized, not because of him, but because of corporate restructuring after Disney’s acquisition of Fox. In an interview, Hamm called his near-casting a ‘brief flirtation’ and admitted it was ‘corporately synergized away’. Now, he’s publicly expressing hope that Marvel might reach out for another role. He’s a lifelong fan, he says, and even joked about Robert Downey Jr. Dominating every iron-clad part. But there’s no confirmation yet. Meanwhile, the rest of the cast is shaping up: Sadie Sink returns as Jean Grey, Christopher Abbott takes on Professor X, Inde Navarette plays Rogue, Maya Boyd is Storm, Kit Connor is Cyclops, Samara Weaving is Emma Frost, and Asa Germann joins as Angel. Before this movie hits, fans will see Channing Tatum’s Gambit clash with Doctor Doom. Played by Downey, in Avengers: Doomsday, which drops in December 2026. The character’s history in the X-Men mythos is deep. Sinister first appeared in X-Men: Apocalypse via a post-credits tease. A briefcase labeled ‘Essex Corp’ containing Wolverine’s blood. Later, in Logan, Transigen used those samples to create X-23. But until now, the man behind the mask has never been seen on screen. And yes, the name change from Nathaniel Essex to Nathaniel Millbury is deliberate. No word yet on how much of the original lore survives. Or whether Driver will wear a mask. Or if Hamm will ever get his shot. One thing’s certain: the X-Men are coming back, and they’re not doing it quietly.