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  • Torchwood, The Sarah Jane Adventures, K9, K9 and Company, Class, Benny New Adventures, Faction Paradox, Iris Wildthyme, Kaldor City, etc.: Many franchises have spun off from Doctor Who, and many of them have later had crossovers, most obviously the Doctor and Sarah Jane appearing on each other's shows every other year. Doctor Who crossed over with Torchwood in "Tooth and Claw", "Army of Ghosts", "Doomsday" (all three aired before Torchwood started), "End of Days" (Torchwood story), "Utopia", "The Sound of Drums", "Last of the Time Lords", "The Stolen Earth", "Journey's End", and "The End of Time", and SJA in "School Reunion" (a 'backdoor pilot' for SJA), "The Wedding of Sarah Jane Smith" (Sarah Jane Adventures story) "The Stolen Earth", "Journey's End", "The End of Time" and "Death of the Doctor" (Sarah Jane Adventures story) (plus flashbacks). In Class the Doctor appeared in "For Tonight We Might Die". K9 from Doctor Who obviously appeared in every episode of his own shows, 'K9', and K9 and Company.
  • EastEnders: The TV special "Dimensions in Time" was a direct crossover between the two franchises. It is largely unpopular.
  • Star Trek: A crossover between Doctor Who and Star Trek: Enterprise was suggested, but never made. In 2012, IDW published "Assimilation²" (comic story), where the 11th Doctor teams up with the Enterprise D crew to fight the Borg and the Cybermen. The Fourth Doctor also appears in one issue, meeting the original Enterprise crew. References to the Whoniverse appear in a number of Star Trek novels, though Doctor Who episodes such as "The Empty Child" and audios such as "Pest Control" (BBC Audio audio story) have established that Trek is fictional in the Whoniverse.
  • Sherlock Holmes: The Doctor has frequently talked about Sherlock Holmes on TV, and they worked together in "All-Consuming Fire" (Virgin New Adventures novel)/"All-Consuming Fire" (Big Finish audio story). Big Finish has its own version of Sherlock Holmes, who has crossed over with Benny Summerfield. (These crossovers are tricky to reconcile with the TV stories since "The Snowmen" established that Holmes was actually Madame Vastra). "Character Assassin" (The Incredible Hulk Presents comic story) revealed that Holmes and Moriarty exist in the Land of Fiction (from "The Mind Robber") and has the Master enter the Land of Fiction to kill Moriarty, whom he is sick of being compared to, and explains why the Master is nothing at all like Moriarty.
  • The Carnacki stories: "Foreign Devils" (Telos novella) has the Second Doctor, Jamie & Zoe working with Thomas Carnacki, the occult detective created by William Hope Hodgson. Carnacki also encountered Iris Wildthyme in "Iris Rides Out" (BF Iris Wildthyme audio story).
  • The famous character of Dorian Gray (featured in his own Big Finish series) has also crossed over with the extended Whoniverse by way of Big Finish's Benny Summerfield.
  • Marvel Comics: The Doctor is apparently part of Earth-616 in the Marvel Multiverse. He's directly crossed over with Death's Head, and had minor indirect connections with Fantastic Four and Transformers.
  • League of Extraordinary Gentlemen: the Doctor is one of many fictional-in-our-world characters who's real in that world.
  • Quatermass: "Remembrance of the Daleks" and "Planet of the Dead" imply that Bernard Quatermass and the British Rocket Group exist in the Whoniverse, and "The Dying Days" (Virgin New Adventures novel) confirms it, but there's been no actual 'crossover stories' as of yet. However, "Autumn Mist" (BBC Eighth Doctor Adventures novel) states outright that Quatermass is fiction.
  • Blake's 7: Direct crossovers were proposed and rejected multiple times, but there are hints that a crossover may finally happen in the Big Finish audios. Meanwhile, there have been minor connections—for example, Carnell appears in the novel "Corpse Marker" (BBC Past Doctor Adventures novel)-even though there have also been direct references to Blake's 7 as a fictional TV show in the Whoniverse. "Death and Diplomacy" (Virgin New Adventures novel) clears this all up by telling us that, coincidentally, Blake's 7 is both a 20th century sci-fi TV show and a real-life 25th century terrorist group, although Benny is confused by the fact that they're both led by the exact same Roj Blake.
  • Dirk Gently: The Doctor and Dirk have never met each other, but they've both worked with Professor Chronotis ("Shada"). (This is due to Douglas Adams recycling material from "Shada", which was never completed for broadcast, in his Dirk Gently novels.)
  • Hitchhikers Guide to the Galaxy: No direct crossovers, but the same books by Oolon Coluphid exist in both franchises ("Destiny of the Daleks"); the Doctor also references Arthur Dent in "The Christmas Invasion" but it's not made clear if he's referring to a book character or an actual person he knows. However, "The Raincloud Man" (Big Finish audio story) refers to The Hitchhiker's Guide as being a fictional franchise.
  • The Simpsons: While Doctor Who is clearly fictional in the Simpsons universe, that hasn't stopped the Fourth Doctor from appearing at least once. He also appeared as a 'representative of television', and Tom Baker himself has appeared as himself dressed as the Doctor. Likewise, The Simpsons is fictional in the Whoniverse (with Homer Simpson's famous "D'oh!" invoked in "Planet of the Ood", but Bart appeared in "Party Animals" (Doctor Who Magazine comic story) alongside literally dozens of characters ranging from John Steed and Emma Peel to Star Trek's Commander Worf.
  • Futurama: The Fourth Doctor appeared in the episodes Mobius Dick and All the Presidents' Heads, and in one of the comics, where Fry mistook him for "TV's Tom Baker".
  • Others: Characters have sometimes made appearances in various, Panel shows, Talk shows and game shows for example both Tom and Collin Baker have appeared as the doctor in "Roland Rat: The Series" as well as Sylvester McCoy appearing as him in "The Noel Edmonds Saturday Roadshow". An Ood appeared to ask a question in "Never Mind the Buzzcocks The Doctor Who Special" as did a Dalek in "The Big Fat Anniversary Quiz" voiced by Nicolas Briggs, similarly K9 appeared on "The Weakest Link - Doctor Who Special" and "Pointless Celebrities - Doctor Who Special" as a contestant both times voiced by John Leeson. The Weakest Link technically already crossed over with Doctor Who in "Bad Wolf"/"The Parting of the Ways" with Anne Robinson voicing herself as a robot. Doctor Who has also quite frequently crossed over with the Cthulhu Mythos. Two examples are "White Darkness" (Virgin New Adventures novel), and "The Nameless City" (short story), from the "12 Doctors 12 Stories Anthology". Another story in the anthology, "The Mystery of the Haunted Cottage" (short story), used the fact it was set in a World of Fiction to include characters such as Dracula, Miss Havisham, and Harry Potter. "The Mind Robber", set in another Land of Fiction, did the same, with characters such as Gulliver (although a later short story retconned 'Gulliver' into really Goth in disguise). Matt Smith played the Doctor in a comedy skit recorded for the 2013 Comic Relief appeal in which the Doctor meets the cast of Call the Midwife. Numerous comedy series have spoofed Doctor Who, however, the TARDIS and the Doctor (apparently in his Fourth incarnation) do make cameo appearances (seen from the distance and unidentified) in an episode of the sitcom Chelmsford 123. Other spoof crossovers include "Comic Relief 2007" (with The Catherine Tate Show), and "The Invasion of Bash Street" (comic story) (with The Bash Street Kids).

For further information, including implied crossovers & incidental references to characters from other franchises, see Crossover.