
The fourteen (and counting) faces of the Doctor, and the TARDIS. note
"It all started out as a mild curiosity in a junk yard, and now it's turned out to be quite a great spirit of adventure."
Doctor Who is a British television institution, and the longest running science-fiction series in the world, first airing on BBC TV on 23rd November 1963. It takes place in and established the Whoniverse, which has a continuous and constantly adapting story involving many different timelines. It also spawned the truly vast Doctor Who Expanded Universe.The premise of the show is simple enough: it follows the adventures of a renegade Time Lord—the Doctor—and their various companions through time and space. The Doctor travels in a living and sentient time machine, the TARDIS (Time And Relative Dimension In Space), and meets many foes, ranging from heavily armoured robots to killer microbes and pollen to — well, members of their own race. Part of the longevity of the series is that when the actor playing the Doctor leaves, the show gets around this by killing the character off, only to "regenerate" the Doctor into a new form played by someone else (sometimes by someone significantly older or younger, or a different gender). As a result, the same character has appeared in the series from the beginning but their new personality and new tastes gives the show a distinctly different atmosphere with each regeneration, and the producers (and, often, fans) treat the introduction of a new Doctor as a relaunch of the series. The show also frequently changes companions (over its history only a relative handful have ever actually stayed longer than one or two seasons), and once again the change in companion is also treated as something of a relaunch, especially in the 2005-present era where the stories are more frequently told from their perspective.The show originally ran from 1963 to 1989 (with an 18 month hiatus in 1985-6 caused by Executive Meddling, during which it "rested" and saw only a radio drama air). In the wilderness years when it was off the air (1990-2004), independent productions ranging from direct-to-video companion adventures minus the Doctor, stories about monsters from the series, spoofs, in-name only stories featuring former Doctors on the show, licence-restricted stories featuring no familiar characters from the series, audio releases, and anniversary specials technically kept the show alive.A Made-for-TV Movie aired in 1996, in which the Seventh Doctor returned at the end of his life and regenerated into the Eighth. This was created as a pilot for a revival, but although the Eighth Doctor became part of the continuity as a whole, no actual return of the series resulted. Between 2001 and 2003, The BBC produced a series of webcasts which it considered in every way an official continuation of the series (insofar as the Beeb ever indicates what is and isn't canon). It is possible more would have been made but for a very exciting development on the television front: in 2005, the BBC regenerated the show. This new revival series is a direct continuation of the old series, rather than being a Continuity Reboot, and the Ninth Doctor was a successor to the classic series incarnations. The revival series has radically upgraded production values (the original series is notorious for its often rubbery monster prosthetics and bad Chroma Key), shorter story arcs but much more continuity throughout, and it introduced deeper Character Development and romance to the series. As such, 2013 marked the show's 50th anniversary. The original show lasted 26 "seasons", whereas the new annual runs of episodes are called "series": officially, the show went from Season 26 to Series 1, and so on. Even subtracting the 16-year "interregnum", the show still holds the record of longest-running English-language sci-fi series, with its nearest rival being the 12-season run of the UK series Red Dwarf.Doctor Who is a British institution and considered a key part of British culture: even Her Britannic Majesty is a fan, and threw the show a birthday party in her palace for its 50th anniversary in 2013. In addition, the Royal Mail honoured the show's anniversary with a set of stamps – one for each Doctor (and the TARDIS) plus the show's villains.The original 1963-1989 episodes are now considered such an important part of the BBC's home video output that they have their own freelance Restoration Team— The First Doctor, "The Sensorites"

- K-9 and Company (1981), a failed Pilot Episode with the Doctor's former companions Sarah Jane Smith and K-9. The episode aired as a Christmas special in 1981.
- Big Finish Doctor Who (1999 - present), prominent audio stories overseen by Nicholas Briggs, starring virtually all the surviving original TV actors. Takes place in a variety of eras and worlds, as with the TV series. Although considered canon by the BBC from the start (and explicitly as of 2013's "The Night Of The Doctor"), Big Finish also has many different timelines/continuities, and includes adaptations of existing works from the Doctor Who Expanded Universe. Due to the audio series' sheer size and complexity, it plays by the rules of the Doctor Who Expanded Universe: the TV series sometimes contradicts or overwrites the audio stories, or adapts them for the televised continuity. Prior to 2015, Big Finish only had the rights to feature characters from the original 1963-89 era, plus the Eighth Doctor from the TV movie (but no other characters from the film); as of 2015, the licence was expanded to include all Doctors and characters introduced prior to the Eleventh Doctor's regeneration in 2013.
- Torchwood (2006 - 2011), a Darker and Edgier (as well as Hotter and Sexier) series focusing on companion Captain Jack Harkness. On indefinite hiatus after four seasons as producer/show runner Russell T. Davies is currently focusing on other projects, although beginning in 2015 Big Finish Productions (see above) started producing audio dramas featuring the original cast.
- The Sarah Jane Adventures (2007 - 2011), a Lighter and Softer kid-friendly spinoff. K-9 put in semi-regular appearances. The Tenth and Eleventh Doctors, and original-series Who characters The Brigadier and Jo Grant guest-starred in one serial each. The series ended production with the death of star Elisabeth Sladen.
- K9 (2010), an Australian children's show (produced by a company other than the BBC) which continues in the spirit of The Sarah Jane Adventures. It takes place in a late-21st-century Dystopian London and features an upgraded version of the robot dog that had been Put on a Bus back in the 1977 story "The Invasion of Time." A single season aired in 2010. In late 2015 plans were announced for a movie to premiere in 2017, but no further official comment has been made since then and there is no indication of such a film being released; the series itself is considered to now be concluded.
- Class (2016), premiering Autumn 2016, this series revolves around a group of sixth formers at Coal Hill School as they deal with typical teenager issues : relationships, school life, monsters from space attempting to destroy all of existence... turns out that the Doctor traveling through time again and again made the walls of space and time stretch thin around Coal Hill, to the point where they are about to burst. As such, who knows what kind of monster might take the opportunity to slip through next. A more adult-oriented series than Doctor Who aimed at the YA crowd (therefore allowing sexual content and violence similar to Torchwood), and produced originally for streaming on BBC Three. Cancelled after its first series due to low streaming and broadcast viewership numbers.

I am the Doctor and you are the tropers:
- For tropes used in specific episodes of the TV series, see the Doctor Who episode recaps.
- For tropes relating to specific characters or monsters, see the Doctor Who characters pages.
- For tropes used in Doctor Who media outside of the TV show, see Doctor Who Expanded Universe.
Recurring examples (that don't fit in one of the three categories listed above):
"One day, I shall come back. Yes, I shall come back. Until then, there must be no regrets, no tears, no anxieties. Just go forward in all your beliefs and prove to me that I am not mistaken in mine."