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
Eternal (Doctor Who) War between the Time Lords and the Daleks, the Eternals were so affected by the violence and the damage to space and time that they left the mainstream five-dimensional universe completely, never to be seen again. Eternal (Doctor Who) The Eternals are a race of cosmic beings first introduced in the "Doctor Who" TV adventure "Enlightenment" with the 5th Doctor (Peter Davison) in 1983. An Eternal who called himself Striker explains to the Doctor that he and his people live outside of time, in the realm of eternity. They consider the mortal inhabitants of the universe to be "Ephemerals", including