The Doctor (Doctor Who) Time Lords a fixed number of twelve regenerations, meaning that every Time Lord had a total of thirteen incarnations including the original. The plot of "The Time of the Doctor" involves the Doctor receiving a new cycle of regenerations from the Time Lords before his expected demise, triggering the regeneration into the Twelfth Doctor, played by Peter Capaldi. The origins of the programme were explored in the docudrama "An Adventure in Space and Time" as part of the 50th anniversary celebrations of "Doctor Who", which starred David Bradley as William Hartnell. Although Time Lords resemble humans, their physiology differs in
Doctor Who: Thirty Years in the TARDIS programme's fiftieth anniversary in 2013, when the one-off special "An Adventure in Space and Time" was broadcast on BBC Two. Doctor Who: Thirty Years in the TARDIS Doctor Who: Thirty Years in the TARDIS is a one-off, 50-minute television documentary, broadcast to celebrate the thirtieth anniversary of the science-fiction series "Doctor Who". It was originally transmitted on Monday 29 November 1993, on BBC One (BBC Two in Scotland). The programme was the first BBC-produced, in-depth documentary chronicling "Doctor Who" since the earlier "Whose Doctor Who" was broadcast in April 1977, although a thirty-minute, categorized compilation of archive clips had been