In its fifty years and eight hundred episodes, Doctor Who has gone through several stunning mythology changes. The Second Doctor’s reign introduced the Time Lords, terrifying unseen beings who judged the Doctor guilty of galactic interference, wiped his companions’ memories, exiled him to earth, and forced him to regenerate—something Tennant’s Doctor described as a type of death. And in fact, this Doctor’s cries of dismay were more miserable and poignant than Tennant’s. For later doctors, the High Council of the Time Lords was a group of stuffy, out-of-touch bureaucrats sending the Doctor assignments or mistakenly accusing the Doctor of crimes—they were the home government, and he, the active agent.
Through it all, the Doctor would regenerate whenever his body grew too old or he met with untimely death. These regenerations were framed as a gift from the Time Lords, though alien biology and a TARDIS were also necessary. 1976’s The Deadly Assassin (Fourth Doctor) announced that a Time Lord can regenerate twelve times (thus allowing thirteen incarnations). In “Death of the Doctor” (on The Sarah Jane Adventures), the Eleventh Doctor says he can regenerate 507 times but it seems likely he’s joking or speaking in code rather than betray a critical weakness to a stranger (5 plus 7 equals 12). Various episodes established that the First Doctor actually was in his original body, as later Doctors occasionally identified themselves as “four” or “eleven.”
There are exceptions to the rule: When the Master uses up his thirteen lives in The Keeper of Traken (1981), he takes over another person to continue living, and in The Five Doctors (1983), the Master is offered a new cycle of regenerations by the High Council in exchange for his help. In the 1996 television movie, the Master attempts to take the Doctor’s remaining regenerations, as the Doctor states that “A Time Lord has thirteen lives and The Master had used all of his.” Nonetheless, the Master is later given more yet again so he can fight in the Time War.
Aside from introducing the concept of stealing regenerations, the film contributed more canon revisions. The Doctor calls himself half-human on his mother’s side (a great puzzle unless he’s lying or joking). For the first time he kisses onscreen as he falls for his companion, an intelligent doctor rather than a screaming ninny. During the decade without new episodes, this Eighth Doctor was the Doctor of novels and audio adventures, with Paul McGann voicing some himself.
The 2005 reboot brought an enormous new following to the show, but has a notably different premise from the previous series and movie. With the Time War wiping out all his kindred, the Doctor becomes an independent agent in truth. There is no central authority, only a single man with a conscience. This Ninth Doctor, Christopher Eccleston, is notably damaged, raw, and angry, compared with his whimsical younger selves. He is no longer just an adventurer, but an ex-soldier in a war he lost. Even after regenerating into quirky David Tennant, the new Doctor describes his immense age and weariness as he often despairs. Only the bright, young companions can divert them. And once again, the Doctor falls in love – David Tennant with Rose Tyler (to say nothing of Madame de Pompadour) and Matt Smith with River Song.
The 50th Anniversary episode rewrote the mythology further—John Hurt is inserted into the lineup as the Ninth Doctor, bumping Christopher Eccleston, David Tennant and Matt Smith up to 10th, 11th and 12th. (Though this War Doctor’s resistance to calling himself “Doctor” means the numbers need not be revised, officially speaking. His first words, after all, are “Doctor no more”). Speaking about the impact of the episode on BBC Three’s After Show program, Matt Smith said: “Steven [Moffat]’s changed the mythology of the character, which after 50 years is an achievement.” Paul McGann returns, establishing not only the movie and subsequent decades of adventures as canon, but drinking a toast to his audio adventures companions and incorporating them into the television universe. This episode also changes the history of the Time Lords, trapping them in a lost pocket universe rather than locking them unalterably in the Time War. The Doctor ends the episode determined to quest for Gallifrey and restore the universe to its status of the classic era. And in the next episode, he finds it.
In the 2013 Christmas Special, “The Time of the Doctor” the Eleventh Doctor reveals that, counting the War Doctor and the Tenth’s partial regeneration in “The Stolen Earth”/“Journey’s End” (2008), he is in his thirteenth and final incarnation. Unable to regenerate, he lives for 300 years in the town of Christmas (compared with some of his regenerations, which don’t appear to have lasted longer than a single year!). However, as Clara begs them to intervene, the Time Lords grant the Doctor a new regeneration cycle, allowing a thirteenth regeneration into the official Twelfth Doctor (Peter Capaldi). During his last scene, Smith’s Doctor tells Clara (and incidentally all the fans): “When you think about it, we’re all different people all through our lives, and that’s okay, that’s good, you’ve got to keep moving so long as you remember all the people that you used to be.” Turning to the screen, he adds, “I will not forget one line of this. Not one day. I swear. I will always remember when the Doctor was me.” And he takes off his bowtie for the last time.
With the new Doctor, the oldest actor since the original First Doctor (compared to the youngest ones ever–Matt Smith and David Tennant), the series mythology seems to be reverting to the beginning. Moffat felt an older actor would provide more of a contrast and lessen comparisons (compared with the similar Ten and Eleven, whom the War Doctor thinks sound like babbling children). Moffat added, “I can absolutely believe that the strange old-young Matt Smith will turn into the strange young-old Peter Capaldi.” It’s been stated that this Doctor will not in any way fall in love with Clara. She will travel with a boyfriend who will echo Rose-Mickey or Amy-Rory, but also the many companion pairs who fell in love and married in the old series. More to the point, this Doctor is on a mission to find the Time Lords and restore the balance, returning the series to, perhaps, its mid-series premise of a “secret-agent-man” Doctor taking orders from the higher-ups and interpreting them to his rebellious liking. Many fans wonder if an older Doctor will push away teen viewers used to Tennant and Smith. But only some have noticed how much the mythology may revert to its classic roots.