Elliot Page Vanya Actor Mary J. Blige Cha-Cha Actor Cameron Britton Hazel Actor Tom Hopper Luther Actor David Castañeda Diego Actor Emmy Raver-Lampman Allison Actor Robert Sheehan Klaus Actor Aidan Gallagher Number Five Actor Colm Feore Sir Reginald Hargreeves Actor Adam Godley Pogo Voice John Magaro Leonard Peabody Actor Ashley Madekwe Detective Patch Actor Kate Walsh The Handler Actor Steve Blackman Executive Producer Jeff King Executive Producer Keith Goldberg Executive Producer Mike Richardson Executive Producer