David Bradley has been cast as William Hartnell in the Dr Who 50th anniversary biopic An Adventure in Space and Time.
Bradley will star as Hartnell, the first actor to bring Dr Who to life, in a biopic which will focus on the creation of the long-running BBC sci-fi drama in 1963.
Bradley, who played Hogwarts caretaker Argus Filch in the Potter films, is absolutely delighted to to be offered the part. He said: "I'm absolutely thrilled. Mark Gatiss has written such a wonderful script not only about the birth of a cultural phenomenon, but a moment in television's history.
"William Hartnell was one of the finest character actors of our time and as a fan I want to make sure that I do him justice. I'm so looking forward to getting started."
Bradley recently appeared in Doctor Who itself, playing space pirate Solomon in the episode Dinosaurs on a Spaceship, and is also known for appearing on Game of Thrones and in acclaimed BBC drama Our Friends in the North.
Jessica Raine will also appear as Doctor Who's first producer Verity Lambert. The Call the Midwife star has already signed up for a role in the next series of Who airing on BBC One from March.
Completing the cast is Brian Cox as Sydney Newman, the Canadian producer who helped devise Doctor Who, and Sacha Dhawan as Waris Hussein, director of the show's first ever episode An Unearthly Child.