Harry Potter star David Bradley is to play Doctor Who actor William Hartnell in a TV drama based on the beginnings of the hit British show.
The sci-fi series marks its 50th anniversary this year and BBC bosses have commissioned a special feature about the drama as part of the celebrations.
The TV movie, titled An Adventure in Space and Time, tells the story of the show's creation, and Bradley, best known for playing school caretaker Argus Filch in the Potter films, will play Hartnell - the first actor to tackle the title role.
Manhunter star Brian Cox will also appear in the film as the BBC's former head of drama Sydney Newman, and the script has been put together by Mark Gatiss, a regular writer on Doctor Who.
"I first heard about this role from Mark (Gatiss)," Bradley said of the project.
"When he asked if I would be interested, I almost bit his hand off.
"Mark has written such a wonderful script not only about the birth of a cultural phenomenon, but a moment in television's history."
Gatiss said: "What a cast. I'm utterly delighted that everyone's favourite Time Lord will be in such brilliant and stellar company."
An Adventure in Space and Time will begin filming in February and will air in the UK later this year.