Doctor Who is one of the longest running television series. Doctor Who details a time travelling, regenerating alien called Doctor Who, saving the earth and, on occasion, the universe itself. It began in 1963 as a one season science fiction serial and is now continuing strong 50+ years later due to regeneration, a staple of the series. Regeneration is a process that happens when The Doctor is dying and he must change every cell in his body in order to survive, which is one of the reasons why there are so many iterations of The Doctor and has been alive for over 2000 years.
The Christmas Special, Twice Upon A Time is the final adventure for the current Doctor(12th), played by Peter Capaldi, who is confirmed to regenerate into Jodie Whittaker, the 13th iteration of Doctor Who, and the very first female Doctor since the show’s inception. The 1st iteration of the Doctor will be in the special as there will be two regenerations in the Special.
While the original actor, William Hartnell died in 1975, the 1st Doctor will be played by David Bradley, who played as William Hartnell in the real life story of the production during the 1963 serial of Doctor Who called An Adventure in Space and Time.
The Christmas Special, Twice Upon a Time, will air on Christmas Day at 9pm on BBC America.