[[quoteright:338:[[VideoGame/DreamMixTVWorldFighters http://static.tvtropes.org/pmwiki/pub/images/mascot_fighter_ftw_1928.jpg]]]]
[[caption-width-right:338: Let's see... [[Franchise/{{Transformers}} Optimus Prime]], [[Anime/{{Beyblade}} Tyson]], [[VideoGame/AdventureIsland Master Higgins]], VideoGame/{{Bomberman}}, [[VideoGame/BloodyRoar Yugo]], VideoGame/TwinBee, [[Franchise/{{Castlevania}} Simon Belmont]]... just to name a few.]]

->''"So many heroes from so many dimensions! This is [[RuleOfCool pretty cool]]!"''
-->-- '''[[WesternAnimation/MyLifeAsATeenageRobot Jenny Wakeman]]''', ''[[VideoGame/NicktoonsUnite Nicktoons: Attack of the Toybots]]''

A {{crossover}} that involves characters from more than two works of {{ficton}}. More often than not, this is a mash up of series which do not have a strict sense of continuity or a clear UniverseBible. To lessen {{canon}}-faulting, especially with series that do have strict continuity, a new 'neutral' setting is made that offers equal footing for all the characters. It also becomes more viable the farther you get from canon, such as one-time TV specials and especially video games. As {{Story Arc}}s have become more prevalent, this practice has somewhat lessened, with shifts to strict [[TheVerse Verse]] building and explicit references.

This rarely occurs in live action shows, unless a production company can be formed that holds copyrights to everything. Thus, this is much more common in animated works -- although you can generally expect Creator/TheBBC to pull one out of somewhere when Series/ChildrenInNeed or UsefulNotes/ComicRelief rolls around.

This trope has become increasingly common in video games, especially those involving both licensed and original properties. These games, depending on how far or how deep they mine, can have interesting effects on the fiction chosen. Many long-gone and/or forgotten HumongousMecha shows, for example, often get a new lease on life, or even a brand-new sequel or remake, after making an appearance or two in a ''VideoGame/SuperRobotWars'' game. Similarly, the ''Franchise/FireEmblem'' series was finally brought over to the US to great success after two of its characters made an appearance as unlockable fighters in ''VideoGame/SuperSmashBros Melee''.

This trope is OlderThanFeudalism. The ''Argonautica'' by Apollonius Rhodius (3rd century BCE) features nearly every ancient Greek mythical hero all going on a quest to find the Golden Fleece.

{{Sub Trope}}s:
* CrisisCrossover (a company-wide Massive Multiplayer Crossover)
** CrossThrough (a company-wide event that affects every series involved without having them cross over)
* DeconstructionCrossover (when the main purpose of using a Massive Multiplayer Crossover is {{Deconstruction}})
* MonsterMash (classical movie monsters)
* UltimateShowdownOfUltimateDestiny (When the Massive Multiplayer Crossover meets LetsYouAndHimFight)

See also PowerCreepPowerSeep and StoryBreakerTeamUp. AllStoriesAreRealSomewhere is related.

----
!!Examples with sub-pages

[[index]]
* MassiveMultiplayerCrossover/FanWorks
* MassiveMultiplayerCrossover/{{Literature}}
* MassiveMultiplayerCrossover/LiveActionTV
* MassiveMultiplayerCrossover/{{Music}}
* MassiveMultiplayerCrossover/VideoGames
* MassiveMultiplayerCrossover/{{Webcomics}}
[[/index]]

!!Examples without sub-pages

[[foldercontrol]]

[[folder:Advertising]]
* A [=MasterCard=] commercial featured several food mascots (from Count Chocula to the Pillsbury Doughboy) eating dinner -- with 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 Met Life 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/JusticeLeague Justice League Unlimited]]'', ''Franchise/{{Ben 10}}'', and ''WesternAnimation/GeneratorRex'' all existing in the same universe, before the end of the Age of Superheroes happened.
[[/folder]]

[[folder:Anime & Manga]]
* The ''Manga/GiantRobo'' OVA series featured characters taken from several other series Misuteru Yokoyama -- the original creator of ''Giant Robo''/''Johnny Sokko and His Flying Robot'' -- had written. This included adaptations ''Literature/RomanceOfTheThreeKingdoms'' and ''The Water Margins'', which led to many main and secondary characters in ancient Chinese clothing coexisting with people in three-piece suits TwentyMinutesIntoTheFuture. It also included the very first MagicalGirl, ''Mahotsukai Sally'' (''Sally, the Witch''), under her original name "Sunny", as Shockwave Alberto's daughter.
* Legendary Manga creator Creator/OsamuTezuka similarly uses {{Reused Character Design}}s in his "Star System", wherein a character from a previous work will actually play a different role in another story, [[AnimatedActors as if they were an actor or actress]].
* ''[[http://www.bedetheque.com/Couvertures/DragonFall5_17022007.jpg DragonFall]]'' blended ''Manga/DragonBall'', ''Franchise/StarWars'' and [[http://fr.wikipedia.org/wiki/Dragon_Fall a whole bunch of other series]] into a parody. With mixed results.
* The intro to the Creator/RumikoTakahashi gallery show ''[[http://www.youtube.com/watch?v=kf953nWYSlA It's a Rumic World]]'' explicitly crosses over ''Manga/RanmaOneHalf, Manga/UruseiYatsura,'' and ''Manga/InuYasha''.
* ''Manga/TsubasaReservoirChronicle'' has the characters jumping from AlternateUniverse to AlternateUniverse filled with Creator/{{CLAMP}} characters from their various series. Amusingly, save a select few examples, mostly as [[TheCameo cameos]], the Alternate Universes are hardly ever populated by ''actual'' CLAMP characters, but AlternateUniverse ''instances'' of them.
** Their first crossover happened in ''Clamp Campus Detectives'' since the three main character were in series/stories on their own before CCD: Nokoru Imonoyama in Duklyon, Akira Ijuin in ''20 Mask ni Onegai'' (Man of Twenty Masks) and supposedly Suou Takamura showed up in an old oneshot. Then there was ''X/1999'' where characters from past CLAMP series started appearing, including Subaru, the main character of ''Manga/TokyoBabylon'', as a major character, and during his series set in the early 90s it was said that he would have a role in TheEndOfTheWorldAsWeKnowIt that is X, making for a bit of {{foreshadowing}}.
* ''Anime/ShatteredAngels'' is primarily a crossover of the mangaka and studio's previous works: ''Manga/KannazukiNoMiko'', ''Anime/SteelAngelKurumi'', ''Manga/MagicalNyanNyanTaruto'', and ''Anime/UFOPrincessValkyrie''.
* Before ''Dengeki Gakuen RPG: Cross of Venus'' (mentioned below), there was [[http://www.youtube.com/watch?v=0CksYnT1qO8 this animated short]] produced for Dengeki Bunko's 2007 Movie Festival, featuring chibi versions of characters from ''LightNovel/KinosJourney, LightNovel/{{Inukami}}'' and ''LightNovel/ShakuganNoShana'' (Note that the chibi Shana here is '''not''' [[{{Omake}} Shana-tan]]; for one, ''she'' is the stalker rather than said omake series' Kazumi.).
* While most Creator/GoNagai series contain cameos here and there, ''Anime/ShinMazinger'' goes the whole way. Characters from several alternate versions of ''Anime/MazingerZ'' show up, as well as characters from ''Manga/ViolenceJack'' (itself a DeconstructionCrossover) and the title demon from ''Manga/MaoDante''. Unsurprisingly, this series is being directed by the same man behind ''Giant Robo'', Yasuhiro Imagawa.
** ''Anime/CBCharaGoNagaiWorld'' is a crossover which features SD versions of ''Anime/MazingerZ'', ''Manga/{{Devilman}}'', and ''Manga/ViolenceJack'', with in-story explanations for the characters being SD, and with plenty cameos (such like ''Anime/UFORoboGrendizer'', ''Anime/KotetsuJeeg'' and ''Manga/GetterRobo'').
** Go Nagai has been doing this for a loooong while. Back in the seventies several movies were made by Toei crossing ''Anime/MazingerZ'' with ''Manga/{{Devilman}}'', ''Anime/GreatMazinger'' with ''[[Manga/GetterRobo Getter Robo and Getter Robo G]]'' or ''Anime/UFORoboGrendizer'', or several of them together.
** ''Super Robot Retsuden'', with story and art by KenIshikawa, is an AffectionateParody of those movies. ''Anime/MazingerZ'', ''Anime/GreatMazinger'', ''Anime/UFORoboGrendizer'', ''Manga/GetterRobo'' and ''Anime/KotetsuJeeg'' characters join their forces to face an EldritchAbomination.
** And the ''Dynamic Heroes'' e-manga is a {{Crossover}} featuring ''Anime/MazingerZ'', ''Anime/GreatMazinger'', ''Anime/UFORoboGrendizer'', ''[[Manga/GetterRobo Getter Robo, Getter Robo G]]'', ''Manga/{{Devilman}}'' AND ''Anime/CuteyHoney''.
* The ''Anime/PrettyCureAllStars'' movie series allows the Cures from the past seasons to meet (and be friends with) the new team.
* About a week after the debut of the film ''Anime/DragonBallZ: Battle of Gods'', Goku and his friends turned up in the latest annual ''Manga/OnePiece'' and ''Manga/{{Toriko}}'' crossover episode.
* Creator/KazumaKamachi writes a light novel that crosses over all his works called ''A Certain Magical Heavy Zashiki-Warashi Deals With a Simple Killer Princess' Marriage Circumstances''.
[[/folder]]

[[folder:Comic Books]]
* ''ComicBook/TheLeagueOfExtraordinaryGentlemen'' has a SuperHero team composed of multiple [[PublicDomainCharacter public domain characters]].
* ''ComicBook/CrisisOnInfiniteEarths'' was a massive DC multiverse crossover that attempted to pare down the 837,000 alternate Earths (some populated by the superheroes DC Comics had acquired by buying out other comic book companies over the course of 50 years, others created just to resolve DC's own legendary {{Continuity Snarl}}s) into one world, obliterating many "Alternate Earth" characters in the process.
* ''ComicBook/{{Fables}}'' is about various figures from fairy tales and folklore living secretly in a neighborhood in NYC.
* ''ComicBook/CastleWaiting'' is another multiplayer fairy tale crossover, featuring characters from many different tales living together in a castle.
* ''ComicBook/{{Planetary}}'' is about an investigative super-team in the Creator/{{Wildstorm}} universe. Their members have had run-ins with {{Dracula}}, Franchise/SherlockHolmes, Jenny Sparks from ''ComicBook/TheAuthority'' and multiple versions of Franchise/{{Batman}}.
* ''[[ComicStrip/DykesToWatchOutFor The Indelible Alison Bechdel]]'' offered a mash-up of various lesbian and gay comic artists, who threw their characters into the same world for a party. As the mash-up included Diane [=DiMassa=], creator of ''Hothead Paisan: Homicidal Lesbian Terrorist'', the results were hilarious.
* ''ComicBook/JoeTheBarbarian'' does this in a manner similar to ''The Indian In the Cupboard''.
* A non-canon ''ComicBook/JudgeDredd'' story in the 1980 ''ComicStrip/DanDare'' annual had Tharg bring all the popular characters currently being published in ''ComicBook/TwoThousandAD'' as well as the Starlord to Dredd's apartment for a surprise party. Then the robots that actually write the comics went on strike, forcing the characters to beat them all up.
* The Creator/AlanMoore comic ''Albion'' shoves together a whole bunch of British comic characters of varying obsurity, most of whom are imprisoned by the Government as part of TheMasquerade.
* ''ComicBook/{{Shi}}[=/=]Cyblade: The Battle for Independents'' featured many independent comic book characters, including ComicBook/{{Cerebus|TheAardvark}}, ComicBook/{{Bone}}, ComicBook/{{Hellboy}}, Comicbook/{{Madman}}, ComicBook/MegatonMan, ComicBook/ScudTheDisposableAssassin, WesternAnimation/TheTick and ComicBook/UsagiYojimbo. Many of the same characters have also appeared in the ComicBook/{{normalman}}/Megaton Man special, ComicBook/{{Gen 13}} ABC and War of the Independents.
* ''ComicBook/FreddyVsJasonVsAsh'', and its sequel ''Freddy vs. Jason vs. Ash: The Nightmare Warriors''.
* Creator/DarkHorseComics had ''Franchise/{{Alien}} versus Franchise/{{Predator}} versus Franchise/{{Terminator}}'', ''Franchise/{{Superman}} and Franchise/{{Batman}} versus Aliens and Predator'', and two miniseries that crossed over ''ComicBook/{{Witchblade}}'', ''Aliens'', ''ComicBook/TheDarkness'' and ''Predator''.
* ''ComicBook/FantasticFour: True Story'' has the FF traveling to the realm of fiction, that is attacked by Nightmare, lord of the dreamworld. To fight him they join forces with [[Literature/TheDivineComedy Dante Alighieri]], [[Literature/SenseAndSensibility the Dashwood sisters]], {{Faust}}, almost all Creator/WilliamShakespeare's protagonists, FrankensteinsMonster, RobinHood, the Literature/{{Ivanhoe}} cast and others, while Nightmare gains allies in the Sheriff of Nottingham, {{Dracula}} and [[Literature/TreasureIsland Long John Silver]]. Many other characters like Franchise/{{Tarzan}} make cameos and in the end Johnny summons [[LawyerFriendlyCameo lawyer friendly versions]] of Film/JamesBond, [[Franchise/{{Transformers}} Megatron]], Creator/StevenSeagal and Creator/ChuckNorris to defeat Nightmare's army.
** ''Comicbook/{{Deadpool}} Killustrated'' is similar, except that the Merc With A Mouth is ''killing'' all the great characters of fiction, in the conviction that if he destroys the heroic archetypes of literature [[RageAgainstTheAuthor the Marvel Universe will never exist]].
* ''[[http://www.comicbookresources.com/?page=article&id=48357 Legenderry: A Steampunk Adventure]]'' is an {{Elseworld}} to various Creator/DynamiteComics universes, in which Comicbook/RedSonja, Franchise/TheGreenHornet, [[Comicbook/TheLastPhantom The Phantom]], Comicbook/{{Vampirella}}, [[Creator/JackKirby Captain Victory, Silver Star]], Series/TheSixMillionDollarMan, Franchise/{{Zorro}} and [[Comicbook/FlashGordonZeitgeist Flash Gordon]] all exist in the same world. Which is {{Steampunk}}.
[[/folder]]

[[folder:Film]]
* ''Film/WhoFramedRogerRabbit'' crossed over Disney characters with characters from Warner Bros. and other studios, saying that they all co-existed with humans [[AnimatedActors as actors in Hollywood]], and that they all hail from "{{Toon}}town", which seemed to be half UsefulNotes/LosAngeles and half AlternateUniverse.
* ''Film/TheMonsterSquad'' had Dracula as the BigBad who controlled all of the other classic movie monsters: FrankensteinsMonster, the WolfMan, the Film/CreatureFromTheBlackLagoon and the {{Mummy}}. There is also a cameo by Abraham Van Helsing.
* [[http://video.yahoo.com/watch/411762/2393937 The Area 52 scene]] in ''Film/LooneyTunesBackInAction'' involved the heroes facing off against Marvin the Martian, who led a group of sci-fi aliens which included [[Literature/TheDayOfTheTriffids a Triffid plant]], the eponymous ''Film/RobotMonster'', the mutant from ''Film/ThisIslandEarth'' and even ''freaking [[Series/DoctorWho Daleks]]!''
* Many Creator/SeltzerAndFriedberg works, such as ''Epic Movie'' and ''Disaster Movie'', could be considered {{Massive Multiplayer Crossover}}s, insofar as they feature many characters and plot elements (or [[ShallowParody weak parodies]] thereof) from recent movies and mash them all together. By all rights, this really ''should'' produce something worth watching on some level.
* A version of this in ''Film/StarTrekGenerations'', which featured the captains of two Enterprises from completely different eras (Kirk and Picard) in the same film. ''Franchise/StarTrek'' has done this numerous times, if you consider the different series separate entities of the same intellectual property.
* ''Film/VanHelsing'', which features the eponymous monster hunter battling Dracula, a werewolf, Frankenstein's Monster, Igor and Mr. Hyde.
* Done with toys in ''Film/TheIndianInTheCupboard''.
* ''Mega Monster Battle Ultra Galaxy Legends The Movie'' fuses many Ultra kaiju from many different series into one movie.
* And with horror-movie creatures in the ''Waxwork'' movies.
* ''WesternAnimation/ToyStory'' features many toys from rival companies as major or minor characters including Mr. Potato Head, Barbie, and LEGO among many others. (And probably some [[{{Expy}} expies]] too.)
* ''Film/TheAvengers'' serves as this for the Franchise/MarvelCinematicUniverse.
* In 1959 a movie was released called ''Alias Jessie James'' starring Creator/BobHope, who was a big fan of TV westerns; he used his clout to include characters from nine different shows in what would turn out to be the first of three Western massive multiplayer crossovers. People appeared in that movie from ''Franchise/TheLoneRanger'', ''Series/TheGeneAutryShow'', ''Annie Oakley'', ''DavyCrockett'', ''The Life and Legend of Wyatt Earp'', ''Series/{{Gunsmoke}}'', ''Series/WagonTrain'', ''[[Creator/RoyRogers The Roy Rogers Show]]'' and ''Series/{{Maverick}}''.
* In the 40th Anniversary ''OOO, Den-O, All Riders: Let's Go Franchise/KamenRider'' has all of the main riders from [[Series/KamenRider Kamen Rider #1]] to ''Series/KamenRiderOOO''.
* The ''WesternAnimation/{{Shrek}}'' films do this to fairy tale characters.
* ''Disney/WreckItRalph'' does this with arcade video game characters.
* ''WesternAnimation/TheLEGOMovie'' features Franchise/{{Batman}}, Franchise/{{Superman}}, Franchise/WonderWoman, Franchise/GreenLantern, Franchise/TheFlash, [[Film/TheLordOfTheRings Gandalf]], [[Film/HarryPotter Dumbledore]], [[WesternAnimation/TheSimpsons Milhouse]], Anime/SpeedRacer, the Franchise/TeenageMutantNinjaTurtles, [[Franchise/StarWars Han Solo, Chewbacca, C-3P0, Lando]]... and that's not including characters from LEGO's own themes!
* ''Film/CirqueDuSoleilWorldsAway'' takes elements from the seven Cirqu Du Soleil shows in Las Vegas.
[[/folder]]

[[folder:Mythology and Religion]]
* The ''Argonautica'' (more commonly known by the adaptation ''Film/JasonAndTheArgonauts'') by Apollonius of Rhodes (3rd century BCE) is one of the very first Massive Multiplayer Crossovers, 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 Massive Multiplayer Crossover 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]]

[[folder:Other]]
* 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.
* ''[[http://edenstudiosdiscussionboards.yuku.com/topic/4219/t/Heroes-and-Monsters-of-the-Millenium-1995-2005.html?page=1 Heroes and Monsters of the Milennium]]'' 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}}'', ''Manga/MahouSenseiNegima'', the works of Creator/HPLovecraft, ''Anime/MazingerZ'' and many others. With considerable overlap in themes, races, and technology.
* 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]]'', a character battle website where a crossover between anything can happen.
* TV Tropes has one for the works of the Walt Disney Company called WMG/FriendsAndTheHighCouncil.
[[/folder]]

[[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 Literature/SherlockHolmes'' edited by Hugh Green. What makes the radio series a Massive Multiplayer Crossover 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]]

[[folder:Roleplay]]
* The number of franchises characters come from in ''Roleplay/CampusLife'' is absurd. In a short list there's ''VideoGame/EarthBound, Franchise/SonicTheHedgehog, Franchise/{{Pokemon}}, [[VideoGame/SoulSeries Soul Calibur]], WesternAnimation/MyLittlePonyFriendshipIsMagic, Franchise/StarWars, VideoGame/{{Pikmin}}, VideoGame/{{Klonoa}}, VideoGame/BlazBlue, VideoGame/{{Portal}}, Franchise/{{Stargate|Verse}}, Franchise/DragonBall, ComicBook/IronMan'', and many, ''[[LoadsAndLoadsOfCharacters MANY]]'' others.
* 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.
* Although there are [[JournalRoleplay many similarly-themed RPs]], ''Roleplay/MilliwaysBar'' deserves mention just for its ''size''. The basic premise is that any character from any fandom can find themselves at the titular bar... and sometimes it seems like just about everyone has.
* Roleplay/TheMassiveMultiFandomRPG, taking place right here on our own forums. ''Anime/PrincessTutu, Manga/{{Naruto}}, Anime/{{Pokemon}}, Franchise/TheLegendOfZelda, VideoGame/NoMoreHeroes'', and ''Literature/{{Discworld}}''- and that's just for starters.
[[/folder]]

[[folder:Stand Up Comedy]]
* There's a ''Franchise/StarTrek''-related comedy routine in which Mr. Spock, [[Film/TwoThousandOneASpaceOdyssey HAL 9000]], and [[Franchise/StarWars 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]]

[[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 [[Literature/{{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/MarvelComics and Creator/DCComics, and the Crusade System lets you pair [[Anime/CowboyBebop Spike Spiegel]], [[Manga/FullmetalAlchemist Edward Elric]], and Anime/CuteyHoney with HumongousMecha from ''[[Anime/SuperDimensionFortressMacross Macross]]'', ''VideoGame/SuperRobotWarsOriginalGeneration'', and countless others.
* Similarly, the ''TabletopGame/HeroClix'' tactical miniature combat game works on a PointBuildSystem basis and includes characters from many comic books (Marvel and DC, 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.
* ''TabletopGame/AniMayhem'', a CollectibleCardGame produced in the middle 1990s by [[Creator/{{Geneon}} Pioneer Entertainment]] that 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.
[[/folder]]

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

[[folder:Web Original]]
* The Game in which ''WebOriginal/LifeInAGame'' takes place seems to take ''all'' video games as true, with [[Franchise/TheLegendOfZelda Zelda]] appearing alongside [[Franchise/{{HALO}} Master Chief]], and [[VideoGame/ChronoTrigger Frog]] serving as the hero's {{Jerkass}} Mentor.
* Website/ThatGuyWithTheGlasses
** The [[WebVideo/TGWTGYearOneBrawl one year anniversary video]]. Basically, in a Chicago hotel 20 contributors of {{Video Review Show}}s beat up one another in an UltimateShowdownOfUltimateDestiny, climaxing in [[spoiler:Super Mega Death Christ vs. Giant Robotic VideoGame/DonkeyKong Jesus riding a puff of smoke]] blowing up. You know what? [[http://thatguywiththeglasses.com/videolinks/thatguywiththeglasses/nostalgia-critic/6719-1-year-anniversary-video Just watch it.]]
-->[[spoiler:'''[[WebVideo/AskThatGuyWithTheGlasses Ask That Guy]]:''']] (''speaking to the various reviewers present'') In fact, I think there's a lot of you who want to do crossovers, aren't there? Because everybody really eats that shit up.\\
'''Everybody:''' Yeah!
** All the cast stayed in Chicago for a couple more days to film crossovers after this. Highlights include [[WebVideo/AtopTheFourthWall Linkara]] being force-read his ''own'' Massive Multiplayer Crossover fanfiction by the Sage, the [[ProfessionalWrestling Ultimate Warrior]] writes a comic series so bad that reality breaks down and Linkara and [[WebVideo/TheSpoonyExperiment Spoony]] keep changing into different AlternateUniverse selves and the Critic and [[WebVideo/TheAngryVideoGameNerd Nerd]] joining forces to review... a Making Of of a Franchise/TeenageMutantNinjaTurtles Tour. Yeah.
** Later on when faced with Uwe Boll's ''Film/AloneInTheDark2005'', the Nostalgia Critic gave up on reviewing it. Until! [[WebVideo/TheSpoonyExperiment Spoony]] and [[WebVideo/AtopTheFourthWall Linkara]] arrived to assist him.
** 2010 kicked off with an epic review of ''Film/DragonBallEvolution'', starring Paw, [=LordKat=], Rollo T, Hopewithinchaos, and Y Ruler of Time, with guests including [[WebVideo/YuGiOhTheAbridgedSeries LittleKuriboh]], [[WebVideo/DragonBallAbridged MasakoX]] and WebVideo/TheHappyVideoGameNerd. This was recorded while everyone was attending [[http://en.wikipedia.org/wiki/MAGFest MAGFest]].
** The [[WebVideo/{{Kickassia}} Two Year Anniversary]] is another huge crossover event. And in turn, it allowed some once-in-a-lifetime crossovers as by this point, quite a few reviewers are from around the world.
** In 2011, things repeated. Y Ruler of Time used [=MAGFest=] to do another multiple reviewer crossover (''Film/TheLastAirbender'', with WebVideo/ToddInTheShadows, WebVideo/JesuOtaku and RolloT, plus various cameos). And Year Three had a [[WebVideo/SuburbanKnights crossover series]] and various individual joint reviews (Todd even opens [[http://thatguywiththeglasses.com/videolinks/thatguywiththeglasses/specials/31178-bmbssm his one]] saying that the trip means crossovers... and gets shot down by three people before [[WebVideo/BadMovieBeatdown Film Brain]] accepts to watch a movie with him).
** And once again in 2012. However, this time it was Linkara that used [=MAGFest=] for a multi-reviewer crossover (''Film/SouthlandTales''), and Year Four had [[WebVideo/ToBoldlyFlee a mini series that's a sequel to the previous one]] and more individual crossover videos.
* [[TropeNamers The original]] ''Music/TheUltimateShowdownOfUltimateDestiny'' flash video. Good guys; bad guys; explosions as far as the eye can see. Way too many pop culture icons to count.
* ''[[http://keisuwabe.shikisokuzekuu.net/page035.html Symphony Of The Blood]]'', a fake video game crossover between all the characters of the [[ReusedCharacterDesign Star System]] of Creator/OsamuTezuka.
* ''Franchise/TheSlenderManMythos'' stories tends to have the blogs mix together. For example, M of ''Blog/TheTutorial'' regularly participates in Damien's blog, ''Blog/DreamsInDarkness''.
* Wiki/TVTropes' very own AlternateRealityGame ''ARG/TheWallWillFall'' has many fictional characters entering the real world.
* Creator/JohnCWright has come up with a [[http://www.scifiwright.com/2014/05/alignments-in-amber/ campaign setting]] (further down the page) which revolves around "anything goes", and incorporates roughly a billion various setting and universes into one complex setting rife with secret societies and inter-universal conflicts.
[[/folder]]

[[folder:Western Animation]]
* Disney owns all the characters it uses plus a whole network. ''WesternAnimation/HouseOfMouse'' has Mickey and Co. as hosts of a nightclub/theater, with the characters of the feature films as the audience.
* Many classic Creator/HannaBarbera characters have been used across the board, in shows like ''WesternAnimation/LaffALympics'' and ''Yogi's Gang''; this is still done, but with a more satirical bent (e.g., ''WesternAnimation/HarveyBirdmanAttorneyAtLaw''). The largest gathering of characters, however, came with a Hanna-Barbera 50th anniversary special in 1989 as all the characters gather together to pay tribute. This doubles as RogerRabbitEffect as they interact with Joe and Bill themselves, along with special hosts Tony Danza and Annie Potts.
* Nearly all recent Creator/WarnerBros animated television series made references and overt cameos with one another.
* The early-90s [[VerySpecialEpisode public service announcement]] ''WesternAnimation/CartoonAllStarsToTheRescue'' had characters like the ''WesternAnimation/{{Teenage Mutant Ninja Turtles|1987}}'', ''WesternAnimation/TheSmurfs'', ''[[Disney/TheManyAdventuresOfWinnieThePooh Winnie the Pooh]]'', the cast of ''WesternAnimation/{{Ducktales}}'', and many others team up to teach a single kid about the dangers of drugs [[spoiler: and save his sister from same]]. Although, if you can see Smurfs, there's a good chance you're tripping balls already.
* The '80s cartoon ''WesternAnimation/DefendersOfTheEarth'' starred King Features' most famous adventure-hero characters: ComicStrip/FlashGordon, ComicStrip/ThePhantom, and ComicStrip/MandrakeTheMagician (along with his sidekick, the [[TheBigGuy strongman]] Lothar).
* Much earlier, in 1972, the one-off animated special ''WesternAnimation/TheManWhoHatedLaughter'' united ''all'' of King Features' popular characters -- meaning not only Flash, the Phantom, Mandrake, and Lothar, but also the likes of ComicStrip/{{Popeye}}, ComicStrip/{{Blondie}}, Snuffy Smith, and ComicStrip/BeetleBailey.
* ''WesternAnimation/CaptainNTheGameMaster'' featured a mishmash of characters who appeared on the NintendoEntertainmentSystem [[InNameOnly done wrong]]. Most of the episodes took place in the neutral Videoland, with characters like [[Franchise/{{Castlevania}} Simon Belmont]], VideoGame/MegaManClassic and [[VideoGame/KidIcarus Pit]] hanging around, even if InNameOnly. Link and Zelda from ''Franchise/TheLegendOfZelda'' (more accurately, from [[Series/TheSuperMarioBrosSuperShow the Zelda cartoon]]) appeared too.
* The Series/ChildrenInNeed music video "Peter Kay's Animated All-Star Band", which features nearly every significant British StopMotion characters with a few 2D British and American characters broadcast "live via satellite", including ''WesternAnimation/RoaryTheRacingCar'', ''WesternAnimation/FifiAndTheFlowertots'', ''WesternAnimation/TheWombles'', ''In the Night Garden'', ''WesternAnimation/AngelinaBallerina'', ''Franchise/ScoobyDoo'', ''Bagpuss'', ''Bob the Builder'', ''WesternAnimation/{{Ben 10}}'', ''Series/{{Thunderbirds}}'', ''WesternAnimation/PostmanPat'', ''WesternAnimation/SpongebobSquarepants'', ''WesternAnimation/FiremanSam'', ''Camberwick Green'', and ''WesternAnimation/{{Paddington}}'' amongst others. [[DoingItForTheArt All singing parts of the characters by their original voice actors. The video took two years to produce, and it's for charity.]]
* Done with advertising mascots in the short film ''WesternAnimation/{{Logorama}}''. It won the 2009 Oscar for Best Animated Short.
* ''The Rosey and Buddy Show'', a 1992 TV special produced by Creator/{{Nelvana}}, featured not only animated versions of Series/{{Roseanne}} and Tom Arnold, but also the Franchise/CareBears, WesternAnimation/{{Beetlejuice}}, WesternAnimation/TomAndJerry, WesternAnimation/{{Droopy}} and even WesternAnimation/{{Wile E Coyote|and the Roadrunner}}'s stunt double.
* Creator/AardmanAnimations made a Google Chrome commercial for Christmas 2012 that featured Franchise/WallaceAndGromit making a conference call with [[WesternAnimation/ChickenRun Ginger]], [[WesternAnimation/CreatureComforts Captain Cuddlepuss and Trixie, the robins]], [[WesternAnimation/ShaunTheSheep Shaun's flock]], and [[WesternAnimation/AMatterOfLoafAndDeath Piella and Fluffles]].
[[/folder]]
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