AMC's upcoming spinoff series "The Walking Dead: Daryl Dixon" has announced several cast members, including Clémence Poésy, who is known for her role as Fleur Delacour in the Harry Potter movies. Poésy will play Isabelle, a killer nun in the new resistance faction called the Union of Hope. The article highlights Poésy's previous roles and mentions her character's involvement in a resistance network. The series is set to premiere on September 10 and will follow Daryl as he navigates the apocalyptic wasteland in France.