David Bradley (born 17 April 1942 in Yorkshire, England) has several credits in and related to the DWU. Most notably, he portrayed William Hartnell, who played the First Doctor and originated the part of the Doctor, in the docudrama An Adventure in Space and Time. He would later portray the First Doctor himself in a surprise appearance in the Doctor Who episode The Doctor Falls, and later Twice Upon a Time. He also reprised the role in in Big Finish Productions' The First Doctor Adventures.
Prior to this, he provided the voice of the Shansheeth in The Sarah Jane Adventures story Death of the Doctor, and played Solomon in Dinosaurs on a Spaceship during series 7 of Doctor Who. Like Colin Baker and Peter Capaldi before him, he has played the Doctor in the TV series proper after having previously held another role on the show.
Outside of the Doctor Who franchise, Bradley is known for, among other things, Broadchurch, written by Chris Chibnall, and for playing Argus Filch in the Harry Potter movies, Abraham Setrakian in FX's The Strain, and Walder Frey in the HBO series Game of Thrones.