[[folder: Advertising ]]

* A [=MasterCard=] commercial featured several food mascots (from Count Chocula to the Pillsbury Doughboy) eating dinner -- with [[CrowningMomentOfAwesome Mr. Clean doing the dishes]].
* USA Network's commercials play this for laughs, having various combinations of characters from their shows (''Burn Notice'', ''Monk'', ''Psych'', others) encounter each other and make idle conversation.
* UK example: [[http://www.youtube.com/watch?v=BCfGC_dGn4M The Greatest Minds In Advertising Join Forces]] in a 2009 viral for ''UsefulNotes/ComicRelief''.
* The MetLife insurance company has released an ad featuring characters from "Peanuts," "Looney Tunes," Hanna-Barbera, and many other animation studios.
* An advertising campaign for Krystal has a red-haired girl, a [[UsefulNotes/McDonalds clown]], and a guy in a [[Advertising/TheBurgerKing creepy mask]] passing up their respective restaurants to get some food from Krystal.
* The [[http://www.youtube.com/watch?v=MuATW92bpmc Origin promo]] for Creator/ToonamiAsia seems to imply this, as we're shown characters from ''WesternAnimation/JusticeLeagueUnlimited'', ''WesternAnimation/{{Ben 10}}'', and ''WesternAnimation/GeneratorRex'' all existing in the same universe, before the end of the Age of Superheroes happened.


[[folder: Mythology and Religion ]]

* The ''Argonautica'' (a.k.a. ''Film/JasonAndTheArgonauts'') by Apollonius of Rhodes (3rd century BCE) is one of the very first {{Massive Multiplayer Crossover}}s, arranged in what would become a fairly classic method -- basically throwing one or two dozen heroes from various separate Greek myth cycles together on a boat with a common mission. This of course makes the MassiveMultiplayerCrossover OlderThanFeudalism.
** Many of the same characters also appear in the story of the Kalydonian Boar Hunt - which, DependingOnTheAuthor, may occur before or after ''The Argonautica''.
* According to some religious studies texts, this has also gone on in many, ''many'' other myths: the most notable involve various saints meeting each other. This goes on even today.


[[folder: New Media ]]

* The Machinima "Beans". Firstly, it crosses over characters from three different series and is made by three different machinima directors, then the storyline involves various internet memes... Oh. And it's made on ''VideoGame/SuperSmashBros''. Making it a crossover on a crossover.
* Technically, any community-made Machinima will have this in spades. [[Machinima/DukeNukemForeverquest Want to see Duke Nukem appear together with some Daleks?]] It's been done.


[[folder: Radio ]]

* Creator/TheBBC Radio 4 series ''The Rivals'' is a series of adaptations of various Victorian detective stories by people who weren't Creator/ArthurConanDoyle, based on the short story collections ''The Rivals of SherlockHolmes'' edited by Hugh Green. What makes the radio series a MassiveMultiplayerCrossover rather than a sequence of unrelated dramas is that Inspector Lestrade is [[CanonForeigner added]] to every story as TheWatson, placing them all in the same [[TheVerse Verse]].


[[folder: RP ]]

* Should be noted that, [[LoadsAndLoadsOfCharacters given the natures of RPs,]] this trope tends to pop up a lot.
* The number of franchises characters come from in Roleplay/CampusLife is insane. In a short list we have Videogame/EarthBound, Videogame/SonicTheHedgehog, Videogame/{{Pokemon}}, Videogame/SoulCalibur, MyLittlePonyFriendshipIsMagic, Videogame/StarWars, Videogame/{{Pikmin}}, Videogame/{{Klonoa}}, VideoGame/BlazBlue, VideoGame/{{Portal}}, Franchise/{{Stargate|Verse}}, DragonBall, IronMan, and many, ''[[LoadsAndLoadsOfCharacters MANY]]'' others.


[[folder: Stand Up Comedy ]]

* There's a ''Franchise/StarTrek''-related comedy routine in which Mr. Spock, the [=HAL=] 9000 computer, and Obi-Wan Kenobi all appear on ''Jeopardy'', in a mental variant of an UltimateShowdownOfUltimateDestiny. [[spoiler: Kenobi is declared the winner, but only because he uses the JediMindTrick on Alex Trebek.]]
* Stand-up comedy troupes sometimes feature a series of comedians who usually headline their own shows:
** ''The Original Kings of Comedy''
** ''The Blue Collar Comedy Tour''
** ''The Comedians of Comedy''


[[folder: Tabletop Games ]]

* The ''TabletopGame/{{Spelljammer}}'' and ''TabletopGame/{{Planescape}}'' settings were designed with this in mind. Spelljammer in particular has rule books dedicated to detailing the Crystal Spheres of settings such as [[{TabletopGame/{Dragonlance}} Krynn]], [[TabletopGame/ForgottenRealms Abeir-Toril]], and [[TabletopGame/{{Greyhawk}} Oerth]]. Where as Planescape has portals to every type of world imaginable.
* {{Collectible Card Game}}s that operate off of a UniversalSystem allow for this; the Universal Fighting System lets you pit [[Franchise/StreetFighter Chun-Li]] against [[VideoGame/SoulSeries Nightmare]], the VS System crosses over {{Creator/Marvel|Comics}} and Creator/{{DC|Comics}}, and the Crusade System lets you pair [[Anime/CowboyBebop Spike Spiegel]], [[Manga/FullmetalAlchemist Edward Elric]], and Anime/CuteyHoney with HumongousMecha from ''Anime/{{Macross}}'', ''VideoGame/SuperRobotWarsOriginalGeneration'', and countless others.
* Similarly, the ''TabletopGame/HeroClix'' tactical miniature combat game works on a PointBuySystem basis and includes characters from many comic books (Creator/{{Marvel|Comics}} and Creator/{{DC|Comics}}, but also "indie" ones); Superman, Dhalsim and Dark Phoenix against Dr. Manhattan, Beta Ray Bill and someone else to match character points is a perfectly reasonable battle.


[[folder: Theatre ]]

* ''Theatre/{{Seussical}}'' has characters from several of Dr. Seuss' books.


[[folder: Other ]]

* ''[[http://edenstudiosdiscussionboards.yuku.com/topic/4219/t/Heroes-and-Monsters-of-the-Millenium-1995-2005.html?page=1 Heroes and Monsters of the Millennium]]'' is a conversion for the UsefulNotes/{{Unisystem}} RPG ruleset, mixing ''Series/BuffyTheVampireSlayer''[=/=]''Series/{{Angel}}'' with everything from ''[[Creator/MarvelComics Marvel]]'' and ''Creator/DCComics'' to ''Series/StargateSG1'', ''Franchise/{{Godzilla}}'', ''Series/{{Ultraman}}'', ''Franchise/LyricalNanoha'', ''WesternAnimation/{{Gargoyles}}'', ''Franchise/{{Negima}}'', the works of Creator/HPLovecraft, ''Anime/MazingerZ'' and many others. With considerable overlap in themes, races, and technology.
* ''TabletopGame/AniMayhem'', a CollectibleCardGame produced in the mid 1990s by [[Creator/{{Geneon}} Pioneer Entertainment]], set characters from many different anime settings -- surprisingly including many series licensed by companies ''other'' than Pioneer -- in a grand romp across their various worlds.
* Wiki/TVTropes' own Pantheon/TropePantheons. Characters from across all fiction gather together as deities, and presumably alternate between annoying each other, and fighting the villains.
* [[http://www.sowhowins.com So Who Wins]], an any-character battle website in which any crossover can happen.
* Wiki/ThisVeryWiki has one for the works of the Walt Disney Company called WMG/FriendsAndTheHighCouncil.
* The Roleplay/FictionalISOTMapGame series of Website/AlternateHistoryDotCom takes its premise as being about 2-dozen or so nations from different works of fiction suddenly being transported to a "blank" Earth without sentient life.


[[folder: Real Life ]]

* UsefulNotes/WorldWarII has something for everyone. ThoseWackyNazis? Check. DirtyCommunists? Double-check. The British fighting on UsefulNotes/TheHomeFront? Yup. {{Eagleland}} pulling a BigDamnHeroes moment for Europe (only after the aforementioned communists had already lost 20 million people)? Why not? And let's not forget about the NuclearOption being used in the East. Everyone got involved in the second World War -- even states that claimed non-involvement such as Spain or Switzerland.