Melee à Trois



"Gabe: Well, isn't the enemy of your enemy, like, your friend? Or whatever? Can't they team up? Tycho: Not exactly. In this setting, the enemy of your enemy is still a floating, greasy, armored brain. Gabe: Well, what about his enemy? Maybe you could be friends with him. Tycho: No, because that guy is a mechanical horror in an undying battle shell. He sails from world to world in a flying tomb, serving gods who eat hope."

- Penny Arcade (on Warhammer 40,000)

This is any fight where there are at least three sides involved, with no prearranged alliances.

We can be talking individuals or armies, although the version with the individuals is usually more fun since the army one often degenerates fast into a free for all. Often noted by directors and fight coordinators as being very difficult to set up or film properly, although often worth it for the aforementioned fun if they manage to pull it off right.

Almost always begins as a Mexican Standoff as the various sides try to figure out who to shoot or stab or fireball first. Things get particularly fun if you have several guys with a gun in each hand, each trying to keep aim on the other two targets simultaneously. Expect a lot of sweating, twitching, and flicking eyes until the inevitable happens.

This trope calls for no prearranged alliances because then it's not really three sided—unless there are so many sides involved that even taking prearranged alliances into account, there are still at least three sides! However, it is fairly common that after a short amount of fighting, two of the sides will accidentally or on purpose end up ganging up on the third, often with an unspoken agreement to finish dealing with each other once the third side is out of the way.

Often enough, this alliance will be helped along when the third side assumes that all its foes are on the same side.

Alternatively, if neither side can win the battle on their own, the outcome depends entirely on whom the weakest of the three will ally themselves with, resulting in the Kingmaker Scenario.

Alternatively alternatively, a particularly devious side may manipulate the others into Let's You and Him Fight, then go after whoever is left.

In a video game, especially a First-Person Shooter, 99% of the time the 3 sides will consist of the player and any allies vs. enemy soldiers vs. some sort of monsters/aliens/zombies.

The trope name comes from the French phrase "Ménage à trois" which basically means a threesome. YMMV if that's connected to what Melee à Trois means.

Compare Gambit Pileup, which is like this trope but with gambits instead of fights.

Anime & Manga

 * Multiple times in the Gundam multiverse:
 * Zeta Gundam: Titans vs. Axis Zeon vs. AEUG. The most memorable of the Free for Alls, homages of this set-up continue down to Gundam 00.
 * Gundam ZZ briefly dabbled in AEUG vs. Zeon vs. Blue Team during one episode, but that was quickly swept away once the titular mech showed up. However, at the end of the series it does essentially become a showdown between the AEUG, Neo Zeon, and.
 * Gundam Wing: Gundam Team vs. World Nation vs. White Fang (though eventually, the Gundams decide to side with the World Nation, mainly because White Fang is the actual threat)
 * Gundam X: Vultures vs. New United Nations Earth vs. Space Revolutionary Army
 * Gundam SEED and Gundam SEED Destiny: ZAFT vs. Earth Alliance vs. Orb the Three Ships Alliance
 * Gundam 00: At the start of the series, the main conflict would be between the three major power blocs of the Union, the HRL, and the AEU. Also known in modern times as the United States, Communist Russia and China, and the European Union, but mostly actually just small conflicts in the middle east in countries supported but not formally belonging to any one of these and no major war.
 * A variant of this exists twice in Gundam AGE. First, we have Zalam and Euba fighting eachother, with Flit fighting to stop Zalam and Euba from fighting, and later we have the Diva's crew who wants to destroy the UE, the corrupt Earth Government who wants to capture Grodek and the Diva, and the UE who just seems to be killing everyone they see mercilessly...
 * Jubei-chan 2 has this; Jiyu vs. Freesia. vs Kita. Kita was the weakest of the 3, but Jiyu and Freesia couldn't ever focus on him because of each other. That is, until
 * Pulled off near the beginning of Liar Game... actually, most of the time.
 * Martian Successor Nadesico, as a series, is a three-way running brawl between The Federation, Corrupt Corporate Executives, and an Alien Invasion. Sometimes the former two work together, sometimes they don't, and the titular Cool Ship is always stuck in the middle.
 * About two thirds of the way through Death Note,
 * At the end of Outlaw Star, Gene and the crew of the Outlaw Star vs. the MacDoogal Brothers and Gwen Khan vs. the Kay pirates. The C'tarl C'tarl Empire also shows up outside the Leyline, but is unable to get in.
 * Naruto: Tsunade vs. Jiraiya, Shizune and Naruto vs. Orochimaru and Kabuto. Although Tsunade takes up Jiraiya and Naruto's side more or less right away, she does first poison Jiraiya.
 * One Piece situation: Whitebeard and his entire fleet is attacking Marine Headquarters, where the Admirals, Seven Warlords of the Sea, and all the important Marines have gathered. Luffy just brought in the Impel Down convicts. Also on board are Crocodile and Jimbei, who do not feel any particular loyalty to him. Meanwhile, And some random guy with a propeller stuck in his head and two peg legs  just got a brief spotlight implying another side is about to start.  So! Seems to all be over now.
 * The Survival Game in Skypiea is a struggle between three factions; the Straw Hats, who want the gold, the Shandians, who want to reclaim their homeland, and Eneru's minions, who want to see who is worthy to go to Endless Vearth. The Ordeal of Iron features Zoro and Gan Fall vs. Wyper and the Shandians vs. Ohm and the Enforcers vs. a giant snake that swallowed Luffy, Nami and Aisa.
 * In the Water 7 Arc, while Luffy and Franky are fighting each other over their respective grudges (Luffy has a grudge against Franky for attacking and robbing Usopp, while Franky wants revenge against Luffy for destroying his house), the Galley-La shipwrights attack Luffy because they believe he sent Robin to shoot Iceberg, and attack Franky for getting in the way, as he doesn't appreciate their taking on Luffy.
 * In Darker than Black, just about every intelligence agency in the world is out for every other one's blood, which is only exacerbated by the activities of The Syndicate and PANDORA. And then gets involved, making the already Gray and Gray Morality into an even more tangled mess. Things do not get any easier in the second season, either, where we have the CIA, MI6, Japanese special forces, bits of The Syndicate, and Madame Oreille all playing their own games with what's going on, plus.
 * In Code Geass: Nightmare of Nunnally, most of the battles involving Nunnally have this, with Britannia trying to suppress the Japanese, the Japanese trying to defeat Britannia, and Nunnally trying to stop the violence.
 * In Bleach's Bount arc, Byakuya and Ichigo fight Kariya, but Byakuya doesn't seem to care if he hits Ichigo with his attacks, so it looks like this trope at times.
 * Millenium vs. Iscariot vs. Hellsing in Hellsing.
 * In the in Katekyo Hitman Reborn, there are seven teams all doing this; the number seven is kind of an ongoing thing in this manga.
 * Volume 15 of To Aru Majutsu no Index is this. Five organizations from the dark side of Academy City made up of four people each fight it out. Add in how three of the groups have Level 5's, one group hires 5000 mercenaries, and a subordinate of one of the organizations rebels, and you have one book practically made of Crowning Moments Of Awesome

Comic Books

 * The great big battle at the end of Lucifer is between Lucifer, allied with the angels of the Silver City, and Lilith's faction. Halfway through the battle, Christopher Rudd appears leading an army of demons and the damned combined. When his general asks who they're attacking, he responds, "Both. We attack both."
 * Also seen in The DCU's recent mega-crossover Amazons Attack.
 * Sonic the Hedgehog
 * In an issue of, Sonic vs. Scourge vs. Shadow vs. Rob 'O, vs. Metal Sonic vs. Silver... with absolutely no real clear way to tell who's fighting who and when.
 * At issue 162-164, an all-out battle for the crown of Acorn was fought between The Freedom Figthers, Mammoth Mogul and the Destructix and Ixis Naugus and the Arachne. Naugus joins with Mogul during the battle when he was told by him that Mogul was the founder of the Order of Ixis, turning the battle into a simple two-sides war. The battle was interrupted by Dr. Eggman however, and he captures Mogul, Naugus and their forces back to his capital prisons. The Freedom Fighters won but at the cost of.
 * And during one of the Sonic Universe arcs, we end up with Team Rose (Amy, Cream and Cheese, and Blaze), Team Dark (Shadow, Rogue, and Omega), Team Hooligan (Nack, Bean, and Bark) and the Babylon Rogues all fighting each other over a Sol Emerald. Teams Rose and Dark briefly team up, but by the end of the story, it quickly devolves into a four-way battle.

Fan Works

 * In Aeon Natum Engel, the escalation of the Iceland invasion led to NEG vs. Order vs. Migou. Then Moloch showed up.
 * The plot of The Dark Lords of Nerima is kicked off when one lone, outcast youma tries to instigate one of these between the sailor senshi, the dark kingdom, and the Nerima crew in order to kill the sailor senshi and get back into the dark kingdom's good graces. They will accept the deaths of many youma if it means killing them.
 * Near the latter end of the Digimon fanfic Zero 2: A Revision, Demon and UmbraDevimon's armies invade the Real World at the same time and immediately start fighting each other, with the humans stuck in the middle. And then the Gravemon show up...
 * In the Danny Phantom/Teen Titans crossover fic HIVEMinded, Jump City ends up as the sight of a brawl between the HIVE, Plasmius' army of ghosts, the Guys In White, the Titans, and the local police forces. Oh, and then the Justice League sends a few members to try and help, but that doesn't work out so well.
 * Shinji and Warhammer40K has a Gambit Pileup with Shinji vs. Gendo vs. SEELE vs. Kaworu. This eventually culminates with an actual melee between NERVs EVAs and Magnos Tancred vs. Kaworu's Warborn vs. Keel Lorenz's MP EVAs, although Kaworu temporarily joins Nerv.
 * In the Naruto fic Hakumei, the heroes return to Konoha to help La Résistance rebel against Danzou... on the same day as the Sand/Sound Invasion, which occurs more or less as in canon. No one realized in advance that there was more than one conspiracy ongoing, so the eventual three-way battle is not good for anyone's plans.
 * Queen of All Oni: The fight in the shrine of the Three Shades—the J-Team goes there looking for information about the Shadowkhan, the Shadow Hand follow them so that Jade can steal a powerful Shadowkhan artifact, and the monks are duty bound to protect said artifact (one of the fragments of a Tome of Eldritch Lore). Of course, since the monks are all True Neutral, they interpret "protect the artifact" as "fight anyone who shows up who isn't there to join the order", so even though they and the heroes are technically on the same side, they fight both them and the Shadow Hand. And it should also be noted that this fight is a total Curb Stomp Battle, as the monks utterly wipe the floor with the other two sides.
 * Team Death Match in Code MENT.
 * The Evangelion/Metal Gear Crossover Evangelion Gear has a three-way war between The Patriots (led by Big Boss), Nerv (led by Gendou Ikari) and Seele (led by Keel Lorentz/Major Zero).

Films -- Animation

 * Princess Mononoke: no less than eight distinct factions, what with San and the Wolves, Ashitaka, Eboshi and Irontown, Jigo and his hunters, the Boars, the Apes, the Deer God, and Asano's samurai. All at cross-purposes. Of course, they aren't all actively trying to kill every other faction, but the resulting tangle is pretty impressive.
 * Batman: Mask of the Phantasm is largely a three-way conflict between Batman, the Phantasm, and Joker, as demonstrated by this nifty color guide. By the time they're all gathered in the same place, though, Enemy Mine has come into effect.
 * Pokémon the Rise of Darkrai, which has the original Japanese title of Dialga vs. Palkia vs. Darkrai. Basically, Dialga and Palkia are having a territorial feud (the reason for which wasn't revealed until two movies later), a battle which they incidentally bring to the town of Los Alamos, Darkrai's home. Darkrai has to protect the town from the two Olympus Mons' rampage, making him the hero of the movie.
 * Tekken: Blood Vengeance has a really impressive brawl between Heihachi Mishima, Kazuya Mishima and Jin Kazama.

Films -- Live-Action

 * Pirates of the Caribbean
 * Dead Man's Chest: Will Turner vs Jack Sparrow vs James Norrington, with Elizabeth standing disgusted on the sidelines. Notably, does not feature two of the sides joining temporarily. Unless you count Will and Norrington both attacking Jack and ducking out of each other's way, but that doesn't last long.
 * At World's End begins this way (Barbossa's pirates vs. British Redcoats vs. Sao Feng's pirates), but the two illegal factions quickly postpone their differences for a later date.
 * On Stranger Tides: Blackbeard's crew vs Barbossa's crew vs the Spanish for control of the Fountain of Youth, with Jack caught in the middle.
 * All of the movies have some point or another where this sort of thing happens. It's almost always Pirates vs. other Pirates vs. Country (Spain or Britain)
 * The original Dawn of the Dead has a climatic 3-way fight between Peter, the zombies and the bikers invading the mall.
 * Face Off features a six-way Mexican Standoff in this manner.
 * The famous climax of The Good the Bad And The Ugly is a Mexican Standoff between the three eponymous leads, well-known enough that almost half of it is in the theatrical trailer, although it stops short of showing the outcome. Although a picture of the scene would make a good trope-picture, it turns out to have a minor subversion since
 * Parodied in the film Anchorman, when a brawl between rival news broadcast teams escalates to ridiculous levels as all the other stations in the city show up one by one.
 * The Matrix
 * In The Matrix Reloaded, Morpheus and Trinity vs. the Merovingian's twin wraiths vs. two Agents, during the highway chase involving the Keymaker.
 * In The Matrix Revolution it was the humans vs the machines vs Smith and his clones.
 * Millionaire's Express is a 1986 Hong Kong movie that appears to juggle a complex set of storylines... until the final 25 minutes or so, when the movie erupted into an all-out anarchic brawl spanning an entire town and involving some of the biggest names in Hong Kong movie asskicking at the time: Sammo Hung, Yuen Biao, Hwang Jang Lee, Cynthia Rothrock, Yukari Oshima, Corey Yuen, Dick Wei, Richard Norton, Lam Ching-ying, and Yasuaki Kurata among them.
 * The film adaptation of Hitman. Agent 47 and three other assassins are at an impasse. However, rather than the usual resolution, they drop their guns, pull out swords, and deal with each other in that manner instead.
 * Of course, it's not entirely clear why the other assassins go at each other, since they're on the same side.
 * District 9 has one around the climax. Wikus and his  versus the MNU Mercenaries versus the Nigerian Gangsters.
 * The fight on the baseball field between  in Mystery Team.
 * During the climax of The Dark Knight, Batman has to take on the Joker, along with his goons and dogs, while simultaneously incapacitating S.W.A.T. officers who have been fooled by a Disguised Hostage Gambit. Saying the S.W.A.T. officers don't cause much of a problem would be an understatement, however.
 * Earlier in the film, the Joker sets one of these up between three goons, forcing them into working for him, but claiming that only one spot is open and holding "try-outs". He leaves a broken pool cue in front of them and leaves, telling them to "Make it fast."

Literature

 * Star Wars: Shadows of the Empire The final battle at Xizor's skyhook has the Empire vs. the Rebels vs. the Black Sun.
 * In one of the Discworld books, a good Dwarf brawl is described as having "100 participants, and 150 alliances."
 * In Sandy Mitchell's Ciaphas Cain novel The Traitor's Hand, the fight against the Chaos forces is greatly simplified by the fact that two separate Chaos factions are on the planet.
 * In Dan Abnett's Ravenor, there are the forces trying to summon a daemon, the forces trying to exploit Enucia, an evil language, and then the Inquisitor Ravenor and his retinue. When the daemon-summoners try to assassinate one of the language forces, Ravenor watches it psychically, making the target assume he had been behind the plot.
 * In the Green Rider series by Kristen Britain, there's a board game called Intrigue which is considered best played with three players in a Mêlée à Trois type game.
 * C. J. Cherryh's Downbelow Station features a war between Earth and the rebel Union that becomes three-sided when the Stations and Merchanters, caught in the middle, form an Alliance so as not to be sold out in a peace treaty between the other two.
 * The Hobbit has the Battle of Five Armies: Elves and Lakemen vs Dwarves vs More Dwarves vs Orcs and Wargs. Gandalf intervenes to get the dwarves to ally with the elves and men right at the outset, however. Other semi-independent factions that join the goodies later on include the Eagles and the Bears of Bjorn.
 * The central plot conflict of Atlas Shrugged has three sides: the strikers, the scabs and the looters.
 * A Song of Ice and Fire features a great number of factions fighting each other, each with their own point of view justifying their actions. This is most overt in the War of the Five Kings, which is Exactly What It Says on the Tin. Even after that war grinds down, new factions rise up or splinter away.
 * In the Warhammer 40,000 novel Deus Sanguinius, a battle between  is complicated when Word Bearers Chaos Space Marines join in.
 * Any Matthew Reilly book will probably have at least one of these. Most of the battles in Scarecrow turned into these, with the heroes repetedly fighting 3 different mercenary armies, as well as whoever they were trying to fight in the first place.
 * At the end of War of the Spider Queen between
 * Volume 15 of To Aru Majutsu no Index has a Battle Royale between, with each having their own goals and motivations.
 * Harry Potter has the Death Eaters versus the Ministry of Magic versus the Order of the Phoenix. No group likes any of the others very much.
 * Romance of the Three Kingdoms has the Shu, Wei and Wu kingdoms all fighting to unite and be The One Ruler of China. It lasted for a dynasty.
 * Redwall
 * At the end of the book Pearls of Lutra, it's Martin II, Grath, and the other heroes vs. Emperor Ublaz and his monitor lizards vs. Rasconza and his corsairs.
 * And in Triss, it's the good guys vs. Princess Kurda and her vermin vs. three giant adders.
 * Nineteen Eighty-Four had Oceania, a totalitarian empire consisting of all of the Western Hemisphere plus Great Britain and the southern half of Africa, fighting Eurasia, essentially Soviet Russia and Continental Europe, fighting Eastasia, a cultist union of China, Japan, Korea and Northern India. They usually united against each other, but also betrayed each other just as easily. Of course, they are almost indistinguishable apart from location and language.

Live-Action TV

 * Mystery Science Theater 3000 episode Warrior of the Lost World features a big fight meet between the various rag-tag gangs who eventually team up to overthrow the evil Empire.
 * Sheridan's forces in Babylon 5 engineer one of these against the Vorlon and Shadow fleets.
 * Jon Stewart, Stephen Colbert, and Conan O'Brien staged one of these over who was ultimately responsible for Mike Huckabee's political showing. This one did start with an alliance, between Stewart and Colbert, but that was quickly abandoned because the true Mêlée à Trois is funnier.
 * The Colbert Nation provides an alternate name for this one: menage a awesome. (Let the record also show that the whole thing was concocted as a way to "waste time on all three of our shows" during the writers' strike.)
 * Buffy the Vampire Slayer: In one episode, a fight breaks out between Buffy vs. a cowboy vampire vs. a horde of innocent bystanders under mind control by a demon. Buffy and the vampire don't actually team up, but they do take a break from fighting each other to focus on the bystanders. A person just tuning in might think they were on the same side.
 * Lost was, for its first three seasons, a conflict between the Oceanic flight 815 crash survivors and the mysterious Others. However, the survivors essentially wiped out the Others in the season 3 finale, just as the third combatant, a freighter with a mercenary team sent to kill everyone on the island, arrived. Both the survivors and the Others had separate conflicts with the freighter, though by the end of season 4 the survivors and Others had teamed up and successfully repelled the freighter.
 * The Tonight Show: The Great Late Night Debate of 2009-2010.
 * Stargate Atlantis developed a three-cornered fight between the Atlantis team, the Wraith and the Asuran Replicators. Although there was never a three-way battle; the closest is when Atlantis pulled an Enemy Mine with the Wraith to take out the Replicators.
 * Has happened more than once in the various Sentai and Power Rangers series. It's a sort of tradition to have The Dragon interrupt a Monster of the Week about to win so he can beat the Ranger(s) himself. Whether this results in a Mêlée à Trois or not varies from series to series.

Music Videos

 * The bizarre abusable child music video addition: What looks like the entire lineup of Cobra Starship does one of these with hidden pies around a table piled with cash in the music video for "The City Is at War". This doesn't really constitute a pie fight, however, as they're meant to be basically gun/knife stand-ins, with being pied in the face being a cause of death.

Professional Wrestling

 * Occurs rather often in Professional Wrestling, in the form of a "Triple Threat Match" or "Fatal Four-Way" (those are the terms used by WWE), or the "Three/Four-Way Dance" (as ECW called it).
 * Ring of Honor uses a combination "four-way" and tag match (separate from a four-way tag team match with eight participants) called "Four Corner Survival," where either of the two 'legal' wrestlers can tag in either of the two wrestlers but only one can win (which is just a cooler name for the old "four corners" match).
 * Matches can go from Triple-Threat Matches to Fatal Four-ways to Six-Pack Challenges to full scale 20-60 man Battle Royals.
 * Stone Cold Steve Austin vs. The Rock vs. Triple H in 1999.
 * This is basically how it looked like the Invasion storyline was going to play out. To sum up: after the WWF (later WWE) very publicly buying out WCW, it turns out that Shane pulled some last-second shenanigans and now "owns" it, and a massive WWF/WCW feud builds up. Suddenly from left field comes Paul Heyman and the ECW Originals, sick of playing second fiddle to the Big Two, especially since their buy out was far more low-key and basically ignored while their wrestlers were quietly filed into place. But then, it turned out he was just The Dragon to Stephanie, who was in fact allied with Shane against Vince, supposedly set-in-stone contractual alliances changed almost on a weekly basis, only a handful of people from either ECW or WCW were saved from becoming jokes, and by the end of it most folks would rather just forget it ever happened.
 * It got so bad that when Vince Russo was eventually re-promoted to the position of head writer of the WWE, his first act was supposedly to suggest relaunching the entire debacle again, YEARS after the whole thing was dead and gone. Debate still rages on whether, if true, it was a case of being so rash as to force them to let him go or simply thinking that doing the exact same thing again would turn out differently, since obviously no one would remember how horribly the last one turned out.

Board Games

 * Sannin shogi is a kind of chess with 3 players playing against each other. However, an alliance is automatically formed if two players gang up on the third.
 * Diplomacy features seven sides, and the only good way to get an advantage is by convincing other players to join with you in ganging up on somebody else. Since the rules are explicitly designed to allow you to lie to other players about what you are going to do in your next move, things quickly get crazy. Many players have remarked that playing Diplomacy is a good way to ruin friendships.
 * And that's just the original, many variants can have up to eleven players, but these boards tend not to be as balanced as the original so some countries are doomed from the start, unless the player is exceptionally good.
 * This is actually quite common in board games, whether the games range from simple to mind-bogglingly complex. Consider Risk and its variants, Twilight Imperium, Dirk Henn's Shogun, and dozens of other examples. Heck, even a lot of games that prohibit direct conflict like Settlers of Catan, Monopoly, etc., allow for the same dynamic as this trope—if you excuse a broad enough definition of "conflict".

Card Games

 * There's a format in Magic: The Gathering, which appropriately enough is called "multiplayer chaos", which consists of at least 3 players against each other, with no predetermined alliances, and no rules saying you must adhere to alliances you make over the course of the game.
 * The card game Munchkin in all its forms lives and breathes this trope. Although it can be played with only two people, it works perfectly fine up to six with just one box set, and even beyond if you have enough expansions, all of which are a side unto their own.
 * Also by Steve Jackson Games, the game Illuminati isn't any fun with fewer than three players. Players can support each other's attacks and defenses, and sides will change rapidly as players approach their respective goals.
 * Poker. And its deformed brother Texas Hold 'Em.
 * Speaking of poker, the Deadlands CCG Doomtown (which uses a poker mechanic to resolve shootouts) can be played this way.

Roleplaying Games

 * In the setting of the RPG Cthulhu Tech, the Aeon War is a grand Mêlée à Trois between the New Earth Government, who want to live, the alien Migou, who want humanity to die so they don't learn more of the mythos and accidentally wake up the Old Ones, and the Cults of the Old Ones, who want the Old Ones to wake up which would result in the death or massive alteration of everyone else. It's a fun time all around.
 * Paranoia has the official agenda of The Computer, the clandestine agendas of over a dozen secret societies, the office politics of several service groups, plus the personal goals of six PCs and as many NPCs as Friend Gamemaster can keep track of. Any two of these may sort-of-align at any given moment (in the sense of "yes, this person will screw me over, but this other person will screw me over faster and harder"), or may pretend to do so. Some official missions up the ante by having everyone pursue the same MacGuffin at once.
 * Since even the heroes of the setting are professional domestic terrorists, Shadowrun tends to turn into this. Corps hire runners to do their dirty work and even if a lot of runners shun wetwork (outright assassination contracts), they aren't above sabotage, bombings, espionage, theft, and occassionally offing some security guards if things get messy. As a result, runners tend to be grey-area men and women working for bad people against other bad people. Other teams of runners rarely cooperate past a pulling a big job together and many will betray eachother for the sake of a bigger cut.
 * To quote one book's fluff: "The only mate a runner should trust is himself... unless some corp brainwashed him into one of those sleeper sorts who go blow themselves up when they heard the phrase 'warm bacon'. Then he probably would be best off not trusting himself either."

Wargames
In general, the forces of Chaos are locked in the four-sided variety of this trope. There are four Chaos gods, and a given Chaos warrior is aligned with one of them and opposed to the other three. The key is getting the four sides to stop fighting long enough to actually accomplish something. But hey, at least they get an army of Demi-Gods by feeding thousands of raw recruits to their chosen champions.
 * Warhammer 40,000. The humans have a policy of extermination for all xenos/mutants/heretics, the Orks are biological war machines, the Eldar consider humans barbarous space monkeys, the Necrons want to kill all life, the Tyranids want to eat everything, and Chaos is... Chaos. The sole exception are the Tau, who are happy to recruit other races into their little space commie family, with force and brainwashing if necessary.
 * Most of the factions above also spend a lot of energy on internal squabbles: the Imperium is constantly engaged in insurrections and reconquests, the Eldar have a break-off group of evil counterparts, the forces of Chaos are divided amongst rival gods, and the Orks will happily fight each other if there aren't any other enemies available. Only Tyranids and Necrons are immune to this in-fighting, the former due to a Hive Mind, the latter because they are mostly mindless servitors.
 * During the storm of chaos in Warhammer Fantasy Battles the Empire is fighting the forces of chaos led by Archaon. Then Grimgor and his orcs turns up, fights their way through both forces, kills the chaos leader to prove that he is the best and goes away—leaving both forces badly damaged. Most worldwide campaigns pit everyone against everyone though. Old Imperium motto used by fans: "The enemy of my enemy is the next one to die.

Toys

 * The Mahri Nui saga in Bionicle has five sides fighting over the Mask of Life: The Toa Mahri need it to save the world, the Big Bad Makuta also doesn't want the world to die but the Toa (justifiably) don't trust him, the Barraki want the mask because it can reverse their mutations and allow them to try conquering the world again, Hydraxon thinks it's too dangerous and must be destroyed, and a Gadunka beast is just territorial.
 * Not to mention that the Mask passes from person to person in the conflict, and some of the Barraki decide to just go solo and escape, leading to an internal conflict within the Barraki group as well. Brutaka arrives at some point to fight Makuta, for reasons of his own. The mad ruler Karzahni also got an interest in the Mask after hearing about it, but
 * Aw, come on. Like your Power Rangers and Transformers and Star Wars figurines and Teenage Mutant Ninja Turtles didn't all fight each other.

Video Games

 * This is often seen in Real Time Strategy video games when there are three or more factions. Generally, the two factions opposing your own are hostile to each other as well as you.
 * Often subverted when the AI drop their differences to kill the player.
 * This shows up a lot in First-Person Shooter video games that feature both enemy human soldiers and enemy monstrous creatures. Typically, the human soldiers and monsters fight each other as well as you.
 * Half-Life
 * Three-way firefights between Gordon Freeman, the Marines, and the Aliens were one of the defining attributes of Half-Life.
 * In Half-Life 2 and the Episodes, it becomes Human/Vortigaunt Resistance vs. Antlions vs. the Combine vs. Headcrab Zombies (although antlions and zombies were rarely in the same place at the same time). The Combine use headcrab shells as a weapon against rebel-controlled areas, and at one point the player gets to control a bunch of antlions.
 * In Opposing Force there are four sides in play (the player and the friendly Marines, the Xen Aliens, the new aliens that have since disappeared from the story and the Black Ops that used to be with the Marines), and with a level editor there could be five (the traditional "enemy" Marines), but without that level editor you never see more than three in the same place at once.
 * Legendary the Box revolves around the Council of 98 (which includes the player) vs. the Black Order vs. the Monsters running amok in the world.
 * The Story Mode in Godzilla: Unleashed consists of four sides: Earth Defenders, Global Defense Forces, Aliens, and Mutants. The sides differ on how they deal with the crystals that arrived from a meteorite and start royally screwing up the Earth, sent by the Big Bad . The Earth Defenders goes out of its way to destroy the crystals, even though their efforts do cause massive property damage. The Global Defense Forces work to stop the monsters running amok from trampling all the cities, and try to maintain order throughout the course of the game. The Aliens are loyal to the Vortaak, and want to use the crystals to conquer and enslave Earth. The Mutants wish to use the crystals for power and are willing to trample anyone to get it, whether they are monsters, humans, or aliens.
 * In Super Smash Bros., you can set up fights as free-for-alls of up to 4 players, or team battles consisting of 2-on-1, 2-on-2, 3-on-1, or 2-on-1-on-1. Technically only if you have four humans. If it's you and three AI, you can count on the CPU going for you instead of another CPU if they have a choice.
 * Averted in StarCraft... most of the time. Despite the seemingly perfect set-up of Terran vs. Protoss vs. Zerg, each race consists of various factions. Infighting ensues.
 * In the novels, the Battle of Tarsonis was depicted as one of these (in the game, there were three separate missions for the battle, allowing them to show that each side was around without having a true melee), with Confederates, Sons of Korhal, Protoss, and Zerg beating the crap out of each other. Mostly, though, the various factions were canny enough to sit back and watch when they found two enemies fighting. Mostly.
 * Another example can be found in Broodwar, when the UED follows Fenix, Raynor and Mengsk to Aiur and not only encounters Fenix' forces there, but also a bunch of Zerg broods that are still around.
 * Warcraft 3 has a few missions where this occurs.
 * In "Reign of Chaos Night Elf 4", the three factions are Night Elves (player), humans and orcs, and undead and demons.
 * "Frozen Throne Blood Elf 3" has the Blood Elves (player), humans, and undead. There are a couple points within the mission where the players has to go through the other two factions fighting it out.
 * Mario Party is in essence a four player free for all (at least in a standard game), but for the minigame at the end of each turn, teams are determined by the color of the space they landed on, leading to basically random and constantly changing 2v2 and 1v3 alliances, as well as free-for-alls if everyone lands on the same color.
 * Devil May Cry:
 * In Devil May Cry 4, there are actually three factions: the Player Characters Dante and Nero, the Order of the Sword, and the Demons. When you're in a battle with enemies from both enemy factions, they will occasionally attack each other instead of Dante/Nero if you stand back long enough and watch the carnage. You're given hints about this situation and later
 * In Devil May Cry 3 before it, there was the conflict between Dante, Vergil and Lady, until  and led the Sons of Sparda to work together against him, while Dante Befriended Lady shortly as well.
 * The final boss battle in BloodRayne is a 3-way fight between Rayne, the super-powered Nazi Commander, and the Devil.
 * Halo: Combat Evolved has Humans vs. Covenant vs. Flood vs. Sentinels, and Halo 2 has Humans vs. Covenant Loyalists vs. Covenant Separatists vs. Flood. In Halo 3, things settle down into a simpler two-way Everybody vs. the Prophet of Truth (and his guard), with  Serves as an inversion and subversion of the FPS case mentioned above, with the  . As   says, "We trade one enemy for another."
 * One Mission in the Magical Battle Arena Lyrical Pack takes this trope and multiplies it by ten (plus 1) with a Gadget Drone Mêlée à Trente-et-Un. Naturally, your mission goal is to be the last Gadget Drone standing.
 * The Item World in Disgaea. In the earliest levels, the "specialists" that you must kill to level up your weapon ignore everything until you attack them, at which point they may counter, but won't attack. Once you get deeper in, however, you see that their "NPC Ally" designation on your map screen isn't just for show, and you may have to pull off some tricky maneuvers to make sure your enemies don't kill them first if they start out too far away.
 * The game Sins of a Solar Empire has this as its basic structure—a three-way fight between different factions with different abilities (tech, psionics, wormhole manipulation). Also, Sid Meier's Civilization series, the Dominion games, (most 4X games, in fact)...
 * Crysis has the USA vs. North Korea vs. Aliens, but only in the expansion game Crysis Warhead. In the original Crysis, the Koreans were killed off. You see Koreans standing around everywhere, frozen solid.
 * Crysis 2 has a similar dynamic, with the US forces fighting both CELL PMCs and the Ceph.
 * One of Samurai Warriors 2's more interesting fights takes place during Hanzo's story, a three-way fight between Hanzo, Kotaro, and Nene (the game's three playable ninjas). Also Kotaro Fuma's Musou Mode in general, where he often doublecrosses his supposed allies and ends up kicking everybody's ass indiscriminately. Then again, he claims to be Chaos... Also, in the first Samurai Warriors, Masamune Date's ENTIRE STORY MODE consists of nothing but him butting in on other generals' conflicts and annihilating both sides without stopping to think overmuch on whose side is right or wrong... or stopping to think at all, for that matter.
 * A few of the battles in Sengoku Basara also involves this. The second game has one in which Keiji butts in on the Betrayal at Honnouji and ends up in a battle between Nobunaga and Mitsuhide (all for the reason of just saying hi to Nobunaga) and one where characters crash a battle between Kenshin and Shingen. The third has certain campaigns ending with the characters intruding in on the Battle of Sekigahara and wiping out both Ieyasu and Mitsunari's army.
 * In Iji, the conflict eventually becomes Iji vs. Tasen vs. Komato.
 * The final mission in The Incredible Hulk: Ultimate Destruction is a frenetic chase and final boss battle between the Hulk, the Abomination, and General Ross' troops.
 * The Final Boss fight of RefleX is a three-way battle between yourself, an alien Humongous Mecha, and two Kamui fighters from the developer's previous game.
 * The fourth to last mission in Super Robot Wars Original Generation 2 takes place in space, just next to a battle between the Einsts and the Shadow Mirrors/Inspectors. Your team arrives to destroy everybody still standing.
 * In Overlord II, it's the well-meaning but idiotic elves, versus the Roman-themed Glorious Empire, versus the forces of the titular Evil Overlord.
 * In the first two Total War games you could end up in this situation if two or more powers attacked a third at the same time. In later games, this kind of massive free-for-all is only possible in the custom battles, but boy could this make for awesome battles if your computer could handle the weight.
 * Armored Core is kind of complicated in a way this trope is played. In 2 it was Zio Matrix vs. Emurade vs. Balena, with the LCC later joining with Balena. But it led to some confusion involving a Civil War between Zio on Earth and on Mars and Balena being caught between the now Corrupted Martian government and the Earth Government.
 * Near the conclusion of Call of Duty: Modern Warfare 2, after, the player is caught in a battle between Makarov's men and , though you're encouraged to let them kill each other off.
 * Trinity and Hilo Monster in Impossible Creatures feature three players in an RTS free-for-all. Also mission of the single-player campaign, between you, the island's caretakers, and.
 * Alien vs. Predator games have Predators vs. Aliens vs. Space Marines
 * Several of the battles in Devil Survivor are like this, and frequently let you choose to intervene on one side or another. In one particularly complex example on Day 6, you have to intervene to stop some demon tamers from escaping the barricade in the midst of a fight between several angels and demons. You can choose to fight either the angels, the demons, or both; meanwhile both the angels and demons will try to kill the tamers before you can defeat them and remove them from battle, resulting in a game over.
 * In Final Fantasy XIII, some Random Encounters will have one group of monsters fighting another group of rival monsters. You can use this to your advantage to take out the stronger group as the weaker ones whittle their health away.
 * Jedi Academy has several examples in different levels, with the player character being the third party.
 * One level has Imperial Stormtroopers and Disciples of Ragnos fighting each other, both also hostile to you.
 * In another, the Disciples release a Godzilla-like mutated Rancor to ravage a city, but it begins eating them just as surely as it will chase you. That doesn't stop the cultists from attacking you while you're trying to run away from the danged thing before it breaks down the wall between you and it and kills everyone on the other side.
 * Most notably, the final levels have the Jedi and students from Luke Skywalker's academy fighting the Disciples of Ragnos. If you've chosen to play the Dark Side, the Jedi will sense your evil and attack you as well. This leads to a number of different Mêlée à Trois situations.
 * In the Drak'theron Keep dungeon of World of Warcraft, the Scourge is attacking the Drakkari ice troll-controlled keep. Both sides are hostile to the player. At the Wrathgate battle, the Horde and Alliance put aside their differences to fight the Scourge until . As a result, in Icecrown Citadel, the player must fight through soldiers of the opposing faction, and board their faction's gunship to fight off the other side's.
 * Red Alert 3 has the Allies vs the Soviets vs the Empire of the Rising Sun.
 * Command & Conquer 3: Tiberium Wars has Global Defence Initiative vs Brotherhood of Nod vs Scrin. The best part of it was that the leader of Nod, Kane, had manipulated all the three factions for his own agenda, and without none of them realizing it.
 * Red Alert 2: Yuri's Revenge has the Allies vs Soviet Union vs Yuri's forces. The Allies and the Soviets allied with each other until Yuri was defeated, then continued to fight against one other, which forced the Soviets to use their own time machine, leading to the events of RA3.
 * In Kingdom Hearts II it was Sora and his allies vs. Organization XIII vs. Maleficent and her allies, and The Heartless regularly changing sides depending which one is the strongest.
 * Syphon Filter 1: Logan & Xing vs. Rhoemer's troops vs. Pharcom. The last act of second game has Logan & friends vs. the Agency vs. the NYPD.
 * The entirety of Shadow the Hedgehog is one huge war between G.U.N./Sonic Heroes, the Black Arms, the Eggman Empire, and the titular hedgehog himself.
 * Averted in Ogre Battle. If there are two or more enemies, they will spontaneously ally against you.
 * Fallout: New Vegas involves an upcoming battle for Hoover Dam (and by between The NCR, Caesar's Legion and Mr. House, with the main character deciding who they want to side with as the Wild Card of the game. Of course, if the players wish, they can even fight for an Independent New Vegas in which they essentially take over Vegas.
 * It gets even more complicated with DLC, which reveals that  also want to wipe out the three main factions competing in the Mojave. And they fully have the means to do it.
 * The plot of Final Fantasy VII quickly becomes a three-way battle between Cloud's group, Shinra and Sephiroth.
 * Prototype starts out as Alex Mercer vs. Blackwatch/US Marines, but shortly thereafter, the Redlight virus and Elizabeth Green hit the scene as well, adding legions of viral mutants to the fray as well. Later on,
 * The uncut Ace Combat 3 Electrosphere eventually had four sides fighting each other in every one of its Multiple Endings: UPEO vs. General Resource vs. Neucom vs. Ouroboros. In fact, each ending was mainly characterized by who your character was fighting for in the end (Ouroboros technically got two).
 * Ace Combat 5 The Unsung War had the setup of Yuktobania vs. Osea vs. in the last few missions. Also, your own squadron had to fight all of them at once until the truth about the third participant went public.
 * Assassin's Creed: Revelations has this, between the Ottoman guard, the Byzantine Templars and their guards, and the Assassins. It's not uncommon to see both of the opposing factions fighting (or sometimes cause it by forcing them to meet somewhere).
 * Saints Row often has the player fighting off both rival gangs and police. Nowhere is this more evident than Saints Row the Third's penultimate mission, "Three Way", where.
 * By the third game in the series, the conflict in Gears of War has the remains of humanity, the Locust, and the Lambent locked in a three way war.
 * Return to Castle Wolfenstein pits you vs. the Nazis vs. the undead.
 * Kid Icarus: Uprising:
 * Pit vs Dark Pit vs Underworld Forces in Chapter 6.
 * Pit vs Space Pirates vs Underworld Forces in Chapter 8.
 * The big one, starting in Chapter 11, is Palutena's Army vs.
 * And then you throw into the mix... Does anybody get along in this game? As a matter of fact, if you stop to pay attention, you will see mooks of different factions beating each other up. Sometimes they'll even kill each other for you so you don't have to.
 * In Sniper Elite, you are an American OSS agent/ColdSniper dropped into the middle of the Battle Of Berlin. You can come across Germans and Russians fighting each other, and can join in whenever you like or simply observe until one side destroys the other.
 * End of Nations the player chooses to side with either the Liberation Front, and the Shadow Revolution, as they fight the Order of Nations and each other.

Web Animation

 * The Flash video series Super Mario Bros Z pits the Mario team (Consisting of Mario, Luigi, Yoshi, Sonic and Shadow) against the Koopa Bros (From Paper Mario) and the Axem Rangers X (Upgraded versions of the Axem Rangers from Super Mario RPG), in a fierce battle on Yoshi's Island. Later, Mecha Sonic appears, who fights against all three, though only one team at a time. He enters the battle by With them down, he then proceeds to  This leaves only the heroes, Mario, Sonic and the gang, to take on Mecha Sonic, and the rest of the episode revolves around this fight rather than the earlier Melee a Trois.

Web Comics
"The enemy of my enemy is my enemy's enemy. No more, no less."
 * During the "Stormbreaker Saga" from Sluggy Freelance, a straightforward battle between the kingdoms of Trent and Mercia is interrupted by K'Z'K attacking both sides with its demon army. Whether any of the Trents or Mercians join sides (besides Torg and Zoe) is unclear.
 * An appropriate quote from Schlock Mercenary:

""I call my proposal 'Giant Dwarf with a hammer'.""
 * In Girl Genius, you have Agatha and her friends, the Jägermonsters (usually on Agatha's side), Castle Heterodyne (supposedly on Agatha's side, but actually a force unto itself), Baron Gilgamesh Wulfenbach and his army (who wants to be on Agatha's side, but can't be), Tarvek and the House Sturmvoraus faction backing him, Zola and the House Sturmvoraus faction backing her, Martellus and the House Sturmvoraus faction backing him, The Other and her minions, Othar Tryggvassen (Gentleman Adventurer!), and... hu... probably many others, including any power-hungry Spark that would get involved. It doesn't simplify things that Honestly, it's more of a Mêlée à Trente-Six.
 * The best illustration of a Mêlée à Trois, though, would certainly be this page.
 * In the Mechanicsburg arc, there were at least seven different factions fighting for control of the city. The old Baron Wulfenbach put the entire city in a time-stasis bubble, stopping the fight cold... with consequences.
 * Homestuck: Vriska vs. Eridan vs.  ! STRIFE!
 * In the web comics of Urban Rivals, the B team have to protect their captured leaders from Zlatars robot ninjas, and the Ghiest clan.
 * The Order of the Stick: This briefly occurs during the Battle of Azure City, when both one of Xykon's duplicates and some ninja assassins sent by Daimyo Kubota try to kill Hinjo. Humorously, the duplicate and one of the ninjas actually argue over who gets the kill, before Hinjo suggests a third option:


 * It looks like the Girard's Gate Showdown will turn into this, with the Order of the Stick vs Team Evil vs The Linear Guild, and that's before you factor in any possible plan the Draketooths (Draketeeth?) may have up their sleeves. It is Girard we're talking about after all

Web Original

 * After the (entirely satirical) feud between The Angry Video Game Nerd and The Nostalgia Critic got really heated, The Nostalgia Critic busted in on one of The Angry Video Game Nerd's autograph signings. Also there was fellow Internet personality Captain S, who wasn't involved with the feud at all but invited himself in anyway, resulting in a slow motion three-way brawl in the parking lot that simultaneously spoofed The Good, the Bad, and the Ugly and Rocky V. It kind of has to be seen to be believed.
 * Cutthroat Forchess.
 * Gym Class.
 * Occurs in Survival of the Fittest on a couple of occasions. For example, Andrew Klock vs. Xian Chun vs. Cole Hudson (becoming Xian and Cole vs. Andrew) and Maxie Dasai vs. Johnathan Rizzolo vs. Emma Babineaux (and turning into Maxie vs. Riz and Emma).
 * The War of the Abridged Series Creators
 * One of Zeon Quest's main deviations from the UC canon is the One Year War turning into one of these.  The news of this causes the royal family to split into the Legitimacy and Loyalist factions.

Western Animation

 * Avatar: The Last Airbender
 * In "The Chase", Azula vs. Aang vs. Zuko. Then one by one the rest of the Gaang shows up, as does Iroh. Eventually collapses into everyone vs. Azula by silent agreement that they all hate her the most. She "surrenders" but gets away anyway.
 * Arguably, this is also present in the rest of the series as a sort of Right Hand Versus Left Hand between Zuko and the rest of the Fire Nation (especially Zhao) fighting over Aang, while Aang is trying to avoid capture.
 * The Spectacular Spider-Man
 * Gang lords auction on a disc with the key to New York. This leads to a battle between Spidey, Hammerhead, Silver Sable, Rhino, and Roderick Kingsley, the guy who actually bought the disc. The winner of the fight?
 * Also, the brawl between Tombstone, Doc Ock and Silvermane in Gangland with Spidey watching from the side, only getting involved to prevent collateral damage. The villains form a (very) brief alliance to take him down, but Tombstone turns on then to maintain his image, as he couldn't be seen in public siding with the bad guys. The winner?
 * After the Foot Clan got taken down a few notches in the 2003 Teenage Mutant Ninja Turtles cartoon, New York became a battleground between what was left of the Foot, the mob, and the Purple Dragons gang.
 * Transformers
 * The second season of Transformers Animated is Autobots vs. the Decepticons still working with Megatron vs. Starscream, with lone enemies like Swindle, Blackarachnia, and Meltdown showing up occasionally.
 * Transformers: The Movie: Autobots vs. Decepticons vs. Unicron.
 * Transformers Energon: Autobots vs. Decepticons vs. Alpha Q and Team Rodimus (before their Heel Face Turn).
 * Transformers Cybertron: Autobots vs. Megatron's Decepticons vs. Starscream's Decepticons.
 * Transformers Prime: Autobots vs Decepticons vs MECH. Recently; also put in an independent-acting and Unicron.
 * The Batman : Batman vs. Catwoman vs. Ragdoll, as they fought over stolen goods.
 * Exo Squad: Exofleet vs. Neosapiens vs. Pirates. Pirates are the Kingmaker.
 * War Planets, a.k.a. Shadow Raiders, involved an ages-long war between four planets, until they are all forced to cooperate because they are attacked by a fifth, far more powerful enemy.
 * Danny Phantom
 * In the episode "Flirting with Disasters", it was Danny vs. Valerie vs. Technus. Danny's prime target is Technus, though he has to shake Valerie off without hurting her. Valerie primary aims for Danny, though being a ghost hunter, she would eventually have aimed for Technus. Technus concentrated more on world dominating, but he would have warded off both of them as he attempted throughout the episode.
 * Also, briefly, Danny vs. Vlad vs. Valerie in "Reign Storm" before they all decided to team up against a bigger foe.
 * In one episode of Kim Possible, Shego, Monkeyfist and Duff Killigan all fight each other for possession of Ron's naked mole rat Rufus. Added awesomeness here as they fight on, in and around the Eiffel Tower, with Kim intervening to save Rufus from harm.
 * In the Avengers Earths Mightiest Heroes episode "Hail Hydra!", there is an Enemy Civil War between HYDRA and A.I.M., with the Avengers trying to stop it, and SHIELD trying to stop everyone.
 * In the Teen Titans episode "Winner Take All", the final battle among friendly competitors is between Robin, Speedy, and Wildebeest. The competitors hold no grudges and are only playing to win the tournament. The fight becomes a one-on-one once Wildebeest loses.

Real Life

 * The Yugoslav Wars were a three-way melee between the Serbs (Eastern Orthdox, backed by the Russians, Greeks and other East Europeans), the Croats (Catholic, backed by Western Europeans) and the Bosnians (mostly Muslim, backed by Arabs and other Muslims). Various alliances were formed and many backs were stabbed in the course of the four-year war.
 * This was also the case in World War Two where the Chetniks (nationalist partisans), Tito's communists and the German occupiers and their allies, most notably the Croat Ustashe were also trying to gain or retain control of Yugoslavia. Tito's eventual victory was not wholly due to Soviet intervention, setting up his rivalry with Stalin and the 1948 split with Moscow.
 * There were many alliances forged, however. You see, Italians weren't really happy with NDH (they didn't even allow NDH forces to cross to south part of the state), partisans were fighting against any occupators for communist, and Chetniks for royalist Yugoslavia, while Germans simply wanted resources from NDH. So Italians often protected Chetniks and Partisans from NDH, and fought them at other times; Chetniks made alliances with Axis forces against Partisans as well with Partisans against Axis; Germans and Ustashi fought Partisans constantly, but sometimes allied with Chetniks against them...
 * The Sectarian civil war that occurred in Lebanon from 1975 to 1990. You may hear it referred to as "war between Muslims and Christians". But in actuality, there were countless factions such as the Phalangists, Palestine Liberation Organization, Amal, Druze, Hizbullah and others. Other countries got dragged into it too. An infamous method of execution that happened during the war was "Identity Killings". Every Lebanese person at that time had an I.D Card which listed their sect or religion. The result was that if you were a civilian trying to get through Beirut in your car, you would come across a checkpoint manned by militants. They would demand to see your I.D, and if you happened to be from a sect that they didn't like, they would pull you out of the car and shoot you in the head. Such behavior by all parties involved characterized the war.
 * The Crusades: Roman Catholics vs. Orthodox Christians vs. Muslims, occasionally pausing to slaughter Jews.
 * And members of all three sides taking the opportunity to attack rivals within their own faction—occasionally with the help of members of another faction.
 * It got more complicated with the Ninth Crusade (1271-1272). Abaqa Khan, the monarch of the Ilkhanate, allied with the Crusaders against the Mamluks. He was a Buddhist. On the other hand, the Northern Crusades (or Baltic Crusades) featured various Catholic factions at war with the last remaining Pagan tribes of Northern Europe. Said Catholic factions rivaled each other and did not hesitate to go into open war. For example the long conflict between Poland and the Teutonic Order. Add a number of Orthodox states, mainly Novgorod, getting involved and you have even more complexity than the Middle Eastern Crusades.
 * The Haitian Revolution: one group wanted to remain loyal to the French Revolution (mostly free blacks, supported by France), one group wanted independence so they could keep things as they were under the monarchy (mostly whites, supported by Britain), and one group wanted independence for a black nation (mostly slaves, supported by Spain). The free blacks won, but when the French Expeditionary Force arrived and started acting like dicks, the free blacks teamed up with the slaves and established an independent Haiti.
 * In many governments, the power is often divided up into three branches, with the idea being that no one branch can get all of the power because it has to compete with two other branches. Apart from the United States of America, many Commonwealth countries like the United Kingdom and New Zealand have seperation of power where the government is split into 3 branches (parliament, judiciary and executive).
 * Many Commonwealth countries also have several parties jockeying for position. As just one example, Canada has had everything from Melees à Trois to Melees à Cinq: The Liberal, Conservative and New Democratic Parties have been competing for decades, with various other parties (Social Credit, Reform, Bloc Quebecois, etc.) being elected to Parliament at any given time.
 * In the old Soviet Union, the Communist Party, the military, and the KGB tended to function as competing political power blocs.
 * Let's not even get started on the causes of the First World War.
 * Many smaller countries went into the war nominally allied with one side but with the full intention of seizing land or other perks from the weakened victor, even if that victor was ostensibly an ally.
 * Several countries backed efforts to establish a southern Slavic state (Yugoslavia) purely because it would weaken the Austro-Hungarian Empire or allow a pretext for war.
 * The "Young Turks" allied with Germany, bringing the Ottoman Empire with them. They then participated in a covert plan to travel the Middle East, fermenting various nations to call for a 'jihad' against the British Empire. To the Germans, this was a tactical plan to force Britian to either expend troops quelling uprisings, or lose India, the crown jewel of it's empire. The Turks, however, intended to use the holy warcry to found an all-Turk empire of the Middle East. The plan failed on it's very first mission to Afghanistan due to a wide array of tactical and diplomatic blunders, as well as the British keeping hefty bribes flowing to Afghanistan.
 * It didn't help that the German agents decided to brew schnapps and get drunk in a country where alcohol was unheard of. Intoxicated European provaceteurs flaunting disregard for local religious laws rarely help under-the-table diplomacy.
 * World War II was arguably one of these, as two separate wars (Japan vs. China in 1937, Germany vs. Poland in 1939) broke out on opposite sides of the globe and eventually merged into a single massive conflict.
 * Indeed, the Chinese conflict was a straight example. The Japanese came and took over the major cities in the eastern area. In theory, this caused the Communists and the Kuomintang to work together to fight a guerilla war against the Japanese. In practice, the Japanese tried to keep control over the area, while the rebels tried to gain popular support, with all three sides taking pot shots at each other trying to remove the competition.
 * Likewise, the Cold War had not two but three main factions: the Western world featuring NATO, the Communist bloc and the Non-Aligned Movement. Adding to the complication was the defection of China which became a power in its own right opposed to the Soviet Union.
 * The term "battle royal" refers to a fight in which three or more combatants fight until only one is left standing.
 * The term was first coined by the Romans to describe gladiatorial fights involving three or more combatants who would fight until one remained standing or alive. Such battles were considered brutal even by Roman standards, such that early Christians such as Clement of Rome and Ignatius actively campaigned against it to no success.
 * The battle royal was revived in the arena of boxing in 19th century America, appearing on the undercard of boxing matches. Before the abolition of slavery, such matches featured five or six black slaves who fought blindfolded and bare-knuckled until either one was left standing or until two fighters remained, at which point the blindfolds were taken off and the fight continued as a normal bout. The practice of the battle royal continued long after the abolition into the early 20th century, with the fighters being allowed to keep their winnings.
 * Nowadays, battle royals occur in Professional Wrestling (see above), with World Championship Wrestling holding the largest battle royals in the industry in the form of the annual 60-man World War 3 pay-per-view events.
 * China has the "Romance of the Three Kingdoms" period that was pretty much this trope.
 * Korea had a similar time period which saw three dynasties battling it out, which were also called The Three Kingdoms.
 * Basically every war on the North American continent before the 1840s involved Native American tribes that could lead to... complicated allegiances and events.
 * The French Revolution which saw the French against more or less everyone at some point, even the US (undeclared naval war). The best example would be the Jacobin Republic, which fought against the British, Austrians and Prussians, while fighting their own civil war against both the moderate Federalists/Girondins in the south and the reactionary Vendeans in the west. The Federalists might have been tolerable to the British, the Vendeans were absolutists like the Austrians, and had they ever met they would have shot each other.