Who Does Jamie Demetriou Play in The Afterparty? Walt Demetriou plays Walt, a graduating class member who didn't leave a big impression and plans to attend the reunion in hopes that someone will remember him. He's been in memorable comedies like Fleabag, Four Weddings and a Funeral, and The Great. He also recently had a supporting role in the Disney prequel Cruella. Image Source: Getty / Mike Marsland