Whoniverse

The universe inhabited by The Doctor. It is a large and unwieldy beast full of internal contradictions. Fortunately, it's a really, really big universe encompassing, er, the entire universe and a history stretching, oh, from the Big Bang to 100 trillion years in the future (plus an alternate universe or five).

The Whoniverse resides in (or sometimes near near) the Softest end of the Mohs Scale of Science Fiction Hardness. Sometimes it's another genre entirely, just with Aliens and Monsters.

The BBC and other copyright holders have never defined what part, if any, of the Doctor Who Expanded Universe is Canon, though the adventure games produced from 2010-2011 are said to have been produced alongside the show as extra "episodes". Further complicating things is that the universe is about time travel, allowing for alternative and overwritten timelines.

The main Live Action TV series set in the Whoniverse:

 * Doctor Who (1963-1989; 1996; 2005-present)
 * K-9 and Company (1981): Single-episode pilot special, involving Sarah Jane Smith and K-9 investigating mysteries in the countryside.
 * Torchwood (2006-present)
 * Torchwood Children of Earth (third series of Torchwood, 2009)
 * Torchwood Miracle Day (fourth series of Torchwood, 2011)
 * The Sarah Jane Adventures (2007-2011)
 * K 9 (2010-present?)

Behind-the-scenes TV series:

 * Doctor Who Confidential (2005-2011): A behind the scenes look at the revived series of Doctor Who.
 * Torchwood Declassified (2006-present): The equivalent to Confidential for Torchwood. Moved to a DVD feature after series 2.

The Doctor Who Expanded Universe:

 * Doctor Who Magazine has included comics since its launch in 1979 as Doctor Who Weekly. Some of these tie in to the other Expanded Universe ranges, most notably the Virgin New Adventures in the 1990s; others have their own continuity.
 * Doctor Who Novelisations
 * Virgin New Adventures (1991-1997)
 * "Continuity Errors" (1996)
 * Bernice Summerfield (1997-1999 in print, 1998-present in audio)
 * Virgin Missing Adventures (1994-1997)
 * Eighth Doctor Adventures (1997-2005)
 * Faction Paradox (2002-2009; 2011)
 * Past Doctor Adventures (1997-2005)
 * Big Finish Doctor Who (1999-present)
 * Gallifrey (2004-2006; 2011-present)
 * Jago And Litefoot (2010-present)
 * Counter-Measures (2011-present)
 * Kaldor City (2001-2004)
 * Scream of the Shalka (2003)
 * New Series Adventures (2005-present)
 * The Darksmith Legacy (2009)
 * Star Trek the Next Generation Doctor Who Assimilation 2 (2012)

Common tropes:

 * Aliens and Monsters: In about 85% of any television set in the Whoniverse. K-9 & Company, in a Subversion of viewer's expectations, had a Scooby-Doo Hoax of one. Torchwood had one episode where the lack of Aliens and Monsters was Played for Drama, and the heroes had to come to terms with ordinary humans being the gruesome villains.
 * Aliens in Cardiff: (Torchwood Trope Namer).
 * Alien Invasion: A signature trope.
 * Aliens Speaking English
 * Aliens of London: (Doctor Who Trope Namer.)
 * All Myths Are True: Vampires, werewolves, fairies, Satan and minotaurs have all appeared, more or less as described by mythology. Other variants of the above have also appeared, including minotaurs... again. And let's not forget two different explanations for the Loch Ness Monster!
 * Ancient Astronauts
 * Beethoven Was an Alien Spy
 * Broad Strokes: Continuity tends to operate on this basis in regards to the universe itself, less so for the characters.
 * Doing in The Wizard: The universe generally and Torchwood specifically, have a tendency to let the wizard live.
 * The show drifted this way over the course of its very long run, starting out as relatively hard science fiction, with some lapses, such as the Celestial Toymaker and the Land of Fiction. The turning point was possibly the Key to Time Story Arc, which featured two god-like Anthropomorphic Personification of Order and Chaos, respectively, and then did not try too hard to call them anything else. Even so, fans complained when Silver Nemesis depicted Lady Peinforte using magic and naming it as such, though this was handwaved the next season as not literal magic, as such, but the work of the Cosmic Horror named Fenric.
 * Earth Is the Center of The Universe
 * Eldritch Abomination
 * Fantasy Kitchen Sink (especially so in the Expanded Universe)
 * Free-Love Future: A central theme in the new series.
 * Heroes-R-Us: UNIT, Torchwood, Sarah Jane's bunch...
 * Invisible Aliens: (The Whoniverse also has several species of literally invisible aliens.)
 * Magic From Technology
 * Magical Database: Torchwood and Sarah Jane have the literal kind. The Doctor's (and Captain Jack's) wealth of knowledge and experience serves as the equivalent.
 * Masquerade: Some modern stories set in the Whoniverse have suggested that ordinary humans have now gotten to accept that aliens exist... Took them long enough.
 * Mr. Exposition: The Doctor, Captain Jack, Sarah Jane, K-9, Mr Smith...
 * Set Right What Once Went Wrong: More commonly, setting things right before they go wrong, often by means of a Stable Time Loop.
 * Sufficiently Advanced Alien
 * Space Is Magic
 * Techno Babble: The Techno Babble phrase Reverse the Polarity, in fact, originated in Doctor Who.
 * There Are No Global Consequences: Played straight in earlier years, but mostly averted on Torchwood and Russell T Davies' run of Doctor Who.
 * Time Travel (as you may have gathered already)
 * Weird Science

For tropes associated with Doctor Who, specifically, see that article.

Debate on the content of the Whoniverse is the stuff of legends. Countless works of the Universe Concordance kind (some official, some not) try to keep them straight. Good luck, folks!