I could be mistaken, but I think I recall the X-Files being syndicated with the “Reopened” tag. Maybe on FX? There may have been some special addenda as well, I vaguely recall a mention of Mitch Pileggi doing some episode introductions.
Our local CBS affilaite (KHOU) shows X-Files: Reopened at 11pm on Sunday, according to billboards I have seen around town. I assumed its just reruns of the regular show since they have older head shots of Mulder and Scully (circa season 1-2).
So Cheers and Seinfeld take place in the same world, yet after pitching their show to NBC, George is upset that the offer they get isn’t as big as Ted Danson’s contract… and in another episode, George Costanza meets George Wendt and tells him they should do the show somewhere other than a bar…
and L.A. Law and Seinfeld are in the same universe, but in one episode George meets Corbin Bernsen and suggests a case they should do on L.A. Law…
I’m sure there are plenty of inconsistencies like that. I might add that The Simpsons would be in that world as well, because of the X-Files crossover, and thus The Critic and King of the Hill would be in that world, and thus it’s one bizarro world.
Millennium with Lance Henriksen (also Chris Carter show) fits - Frank Black made an appearence on an X-Files episode (one with the zombies?)
There’s another connection - The character Jose Chung first appeared in an episode of X-Files, then later in an episode of Millennium.
Personally, I always hoped to see Mulder & Scully investigate all the immortal beheadings.
It depends how you count; I’m inclined only to count mutual crossovers, else someone can do a series which crosses over with EVERYTHING, and then everything is all in one universe, which is going to cause logical problems, because in some universes, other universes are fictional. hypEg. someone on X-files watching startrek on TV.
If you’re fairly genorous, almost all webcomics fall into the same universe as they absolutely love cross-overs.
Television, Television, Television. How about books?
The Lovecraft mythos includes all Conan the Barbarian novels, all Conan rip offs, all Japanes tentacle porn, Marvel comics, The Ghostbuster’s movie, and tv show, Babylon 5, Stephen King (influrnce, tone, and the story “Crouch End”), Lin Carter of Mars, Sam Raimi, H.R. Giger, alot of Heavy Metal songs, The Alfred Hitchcok film “Psycho”, Dark Shadows, Hercules: The Legendary Journeys, Night Gallery, written by a corespondant of Lovecraft’s, Robert Bloch, who I recall setting his stoires in the mythos. (So what if it didn’t involve the old ones, it was in the same universe. )
That is not counting the 41 films accredited to Lovecraft’s work in http://us.imdb.com/name/nm0522454/
If you’re going to count media other than TV you can just stop when you get to comics, the king of the hill. Marvel and DC, which together publish over a hundred comics monthly, are both shared universe companies. DC’s universe stretches back to 1938 or earlier and Marvel stretches back unbroken to 1961 and then intermittently back even more to the '30’s or early '40’s as well. The two universes have crossed over more than once, and they’ve crossed over with Dark Horse, most of the Image studios, and many licensed properties. Even many of DC’s Vertigo series have “crossovers” with the main DCU as strong as some of the ones mentioned on that website.
–Cliffy
I don’t know. I suppose I could count the Marvel comic book line as being a shared universe with Doctor Who, since he is involved in The Origin of Marvel UK/Marvel USA/Transformers villian Death’s Head. Thus, Doctor Who is the bigger universe. Or maybe I’ve got the logic of cross-overs mixed up from reading so much “cast one hero in another universe” fanfiction.
Do a Google search for “Wold Newton Universe,” if you want shared fictional universes. It will make you want to cry, or perhaps puke.
Does putting SF and fantasy writer Lin Carter on Mars crossover Barsoom into the real world? I hop Spirit takes a picture of Dejah Thoris! 
Speaking about real life, I suppose the fact that James bond (January 4, 1900 – February 14, 1989) is a real person, (as I have mentioned before) would make it the biggest extended universe. Since Ian Fleming took Bond’s name without permission, he gave Bond’s family the rights to Fleming’s name.
They’ve done at least one… with The Critic.
I can see how someone could be in denail about it. The critic wriiters might get along with the simpsons writters, but there was a mutiny over the cross over.
http://www.critic.nohomers.net/Special_Extras_Matt_Groening_Reaction.html
On another hand, I see Tom Baker’s appearence on the simpsons to be both a tribute, and a crossover. Come to think of it, doesn’t the sports stars who played themselves on the SImpsons count as a crossover with the real world?
Other than the ones that are explicitly within the DCU cosmology* (Sandman (and spinoffs), Sandman Mystery Theater, Shade the Changing Man, Animal Man, Doom Patrol, Swamp Thing, Hellblazer, The Books of Magic, Phantom Stranger and Zatanna specials, Kid Eternity, and others that aren’t coming to mind right now), which Vertigo books have crossed over with the DCU?
I can only think of one - Flex Mentallo, who was first created for Doom Patrol, then had a miniseries that was, by all indications, unconnected to the DCU.
I don’t remember Preacher or 2020 Visions doing so (although both may have done so further in than I’ve read)…and those 3 are the only ones I’ve read that aren’t in the DCUC
- I say the DCU cosmology, rather than the DCU, since a lot of them take place, in whole or in part, on other planes - the Dreaming, Hell, other Earths and so on - rather than in the Universe, per se - and, come to that, so do quite a few books that aren’t under the Vertigo imprint.
Can’t unspoofed cameos count as crossovers? What about the time Archie, Big Moose and Jughead ran Homer out of Riverdale?
The Punisher once crossed over into Archie comics. Really.
Both of Wally Lamb’s books, She’s Come Undone and I Know This Much Is True, take place in the same universe. In I Know This Much Is True, the main character is a housepainter. He wants to take some time off, so he thinks about subcontracting Thayer Kitchen, a character in She’s Come Undone, to finish up his projects.
All of The Firesign Theatre’s recordings take place in the same universe, since there are tons of cross-references, and characters from one album appear in another. Furthermore, some albums end with the opening sequence on another album.
I’m assuming that merely making some reference to the real world doesn’t count as incorporating the real world–or even part of the real world–into the universe of the fictional work. Otherwise, we’d have an awful lot of enormous universes established in works of fiction.
Alan Ayckborne wrote three plays (collectively known as “The Norman Conquests”), which show the events at one British weekend party. “Table Manners” shows what’s happening in the dining room, “Living Together” shows what’s happening in the living room, and “Round and Round the Garden” shows what happening in the garden. Characters exit from one play and show up in another.