A (political, cosmological or similar) system is made up of certain factions. But at least one of them is missing, its absence leaving a big hole that generates a lack of balance and harmony.

When such a faction is missing, don't be surprised if there is [[LastOfHisKind one member left]].

A faction making a FaceHeelTurn or HeelFaceTurn qualifies only if its change of alignment leads to it no longer being a part of the system. If it's still a part of the system (although now in an antagonistic way), it's not this trope.

Basically, a collective form of The Pete Best.
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!!Examples:

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[[folder: Anime and Manga ]]

* ''Manga/{{Bleach}}''- A subversion. Before the events of the main story took place, there were 5 noble clans of the Soul Society. One of them, the Shiba Clan, plummeted to literally a single household of a few members and servants because of mysterious events relating to Kaien Shiba's death. And possible also to do with, based on various vague hints, [[spoiler:Ichigo's father (long suspected by fans of being a Shiba) defecting from the Gotei 13 and marrying a Quincy]]. The clan does exist, but possesses very little, if any power.
* ''Manga/OnePiece'' goes through this a few times, with the government-ordained group known as the Seven Warlords or the ''Shichibukai'', and the informal quartet of the four strongest pirate leaders known as the Four Emperors. Several times throughout the plot, a gap in one of those groups becomes a significant point. Notably, there was the exposure of Crocodile's plot, leading to him getting booted from the Warlords and his replacement by Blackbeard, who [[spoiler: betrayed the organization to bust out some top-level prisoners from Impel Down]]. In the course of the Paramount War, [[spoiler:Jimbei and Gecko Moria]] were removed from the Warlords, and [[spoiler:Whitebeard, one of the Emperors, was killed.]] Much of the fandom's post-timeskip speculation revolves around determining who has filled the missing slots in the Warlords.

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[[folder: Comic Books ]]

* In ''ComicBook/TheSandman'', there are seven Endless: Destiny, Death, Dream, Desire, Despair and Delirium. The seventh Endless? Used to be Destruction, but he quit. [[spoiler:Turned out that he left because of Newton. He realized that the humans were only centuries away from discovering the nuclear bomb, and he didn't feel up for administrating that again.]]

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[[folder: Film ]]

* Both ''Franchise/StarWars'' trilogies feature a universe where the state of galactic politics is based on the absence of an ancient order. In the original trilogy, it's the Jedi Order. In the prequel trilogy, it's the Sith Order.

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[[folder: Literature ]]

* Literature/TheBible has the Lost Ten Tribes of Israel.
* In the ''Literature/WarriorCats'' series, one of the five Clans, [=SkyClan=], was forced to leave because of the humans' intrusions on their territory, and they eventually died out in their new home. The Clan was eventually rebuilt, but they are no longer part of the system; only a few cats even know of its existence.
* In the DresdenFiles, the sudden extinction of the [[spoiler:Red Court of vampires]] late in the series' run has thrown the political balance of power in the supernatural world way, way out of whack.
* Literature/TheHungerGames- The thirteenth district.
* In the ''StarTrekMyriadUniverses'' series, two of the AlternateHistory stories start with the assumption that one of the founding races of the United Federation of Planets wasn't involved. ''A Less Perfect Union'' shows a xenophobic Earth withdrawing from the Coalition of Planets due to the actions of [[Series/StarTrekEnterprise Terra Prime]], leaving only Vulcan, Andor and Tellar. Humans wind up in a cold war scenario with this "Interstellar Coalition". In ''The Tears of Eridanus'', meanwhile, Vulcan never turns to logic and remains a primitive warlike culture, leaving Andor as the galvanizing force behind the formation of a Federation-equivalent.

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[[folder: Live Action TV ]]

* The Thirteenth Tribe from [[Series/BattlestarGalacticaClassic both versions]] of ''Series/{{Battlestar Galactica|Reimagined}}''.
* The Xindi Avians in ''Series/StarTrekEnterprise''.

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[[folder: Mythology ]]

* There are [[http://en.wikipedia.org/wiki/Legio_IX_Hispana several]] [[http://www.fighttimes.com/magazine/magazine.asp?article=719 tales of a]] LostRomanLegion, which went to subdue a foe, never to be heard from again. Notably, this is one of the concepts JimButcher uses in the ''Literature/CodexAlera'' series.

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[[folder: Tabletop Games ]]

* The TabletopGame/OldWorldOfDarkness had several of these:
** The lost/extinct vampire clans in ''TabletopGame/VampireTheMasquerade'', namely, the Cappadocians and the Salubri. The power vacuum they left behind is filled in by the Giovanni and the Tremere in the Final Nights.
*** There's a bloodline in the Sabbat sourcebook called the Harbingers of Skulls who are pretty obviously the Cappadocians, though. To the point one of their Stereotype Reactions is from a recently-deceased Giovanni: [[CurseCutShort "Oh, sh-"]]
** From ''TabletopGame/WerewolfTheApocalypse'', there are Apis [werebulls], Camazotz [werebats], and Grondr [wereboars], who were wiped out by the Garou [werewolves] during the War of Rage. Among the Hengeyokai (the shapeshifters of Asia), the Akuma--Asian werebears--are extinct. Also, among the Garou themselves, there are the extinct Bunyip and Croatan tribes, as well as the Black Spiral Dancers, who fell to the [[TheDarkSide Wyrm]].
** ''TabletopGame/MageTheAscension'': For the Technocracy's predecessors, the Order of Reason, there were the Craftmasons (mages of the common people) and the Ksirafai (secret police). For the Council of Nine, there were the Solificati (alchemists) and the Ahl-i-Batin (Middle Eastern mystics). The Technocracy's Sons of Ether and Virtual Adepts don't qualify - they switched to the Council.
** ''TabletopGame/WraithTheOblivion'' had a few Guilds that were dismantled by the Hierarchy for the sheer fact that their [[FunctionalMagic Arcanoi]] were open to abuse and anarchy - the Alchemists (who practiced Flux, which allowed them to transform matter in the Skinlands), the Mnemoi (who practiced Mnemonsynis, which manipulated memories; they were originally judges before they did something ''very'' bad), and the Solicitors (who practiced Intimation, which involved manipulating wants and desires - which is powerful, as [[UnfinishedBusiness Passions and Fetters]] entirely define wraiths).
* ''[[TabletopGame/TrinityUniverse Trinity]]'' had two lost psi orders. The Chitra Bhanu, the quantakinetic order, were virtually wiped out by the other orders, who believed them to have become corrupted by the monstrous Aberrants. The Upeo wa Macho, the teleportation order, was absent for part of the metaplot: they'd found not all Aberrants appeared to be monsters, causing the other orders to view them with increasing suspicion. Things came to a head when the other orders delivered the Upeo an ultimatum asking them to defer to the orders or face the consequences, which led to the Upeo disappearing from Earth altogether for several years.
* ''TabletopGame/LegendOfTheFiveRings'': When the Children of Heavens descended (i.e. fell) to the world, [[OddNameOut Fu Leng]] landed on the [[{{Mordor}} Shadowlands]], and thus didn't create his own (human) lineage in Rokugan. Though if you really want to stretch it, [[AlwaysChaoticEvil Spider Clan]] can claim descend from him. The rest of the Children of Heavens don't seem to mind losing their brother.
* ''{{Exalted}}'': Each type of Exalts (and caste of [[HumongousMecha Alchemicals]]) have a magical material associated with them: [[MadeOfWin Solars]] with Orichalcon, [[BarbarianHero Lunars]] with Moonsilver, [[{{Ninja}} Sidereals]] with Starmetal, and [[ElementalPowers Dragon-Blooded]] with Jade. However, two of the existing magical material don't have 'proper' associated type of Exalts: [[AndIMustScream Soulsteel]], and Adamant. [[FaceHeelTurn Abyssals]] make good use of Soulsteel, but their method is noticably crude; the material isn't really meant to be used by them. The 'lost' Exalts were likely wiped out during the [[EarthShatteringKaboom Three-Sphere Cataclysm.]]

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[[folder: Video Games ]]

* ''VideoGame/VegaStrike'' had the Lightbearers in the {{backstory}}.
* ''VideoGame/GoldenSun'': A lot is made about the Anemos tribe, of which two major characters are descendants and whose entire city apparently lifted off to become the Moon. Guess who ''doesn't'' show up in ''Dark Dawn''?
** Because of her mysterious backstory, it's widely speculated that Sheba may also be from Anemos.
* The mythical 11th clan of S'pht, the S'pht'Kr from ''VideoGame/{{Marathon}}''. On a related note, the S'pht homeworld's mythical third moon, K'lia.
* The Androsynth from ''VideoGame/StarControl 1'', absent in ''VideoGame/StarControl 2''. [[BerserkButton Do not ask the Orz what they have done to them, and why.]]
* The fifth house, Hispania, in ''{{Freelancer}}''. What actually happened was their colony ship sputtered out before it reached a habitable planet (unlike the Liberty, Kusari, Bretonia, and Rhineland colony ships), so its survivors and descendants became space-faring pirate clans.
* The backstory to ''VideoGame/{{Homeworld}}'', which is literally AllThereInTheManual, goes into great detail about how Kushan society is broken up into tribe-like structures known as Kiiths. Every Kiith participated in the construction of, and has a place on the mothership intended to take their people back to Hiigara--except for Kiith Gaalsien, which was wiped out in a sectarian war. And don't even get started on the [[TomatoSurprise Kadesh]].
* ''{{VideoGame/Touhou}}'': The Oni, who used to dwell in the Youkai Mountain along with the Tengu and the Kappa. The last known surviving member, [[DrunkenMaster Ibuki Suika]], is the star of Touhou 7.5, which is titled ''Immaterial and'' '''''Missing''''' ''Power''.
** Turns out they are really just hiding: the majority of the Oni retreated underground into the Former Hell. One of them being Hoshiguma Yuugi. Another character, Kasen Ibara, is also suspected of being an Oni.

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[[folder: Western Animation ]]

* In ''WesternAnimation/AvatarTheLastAirbender'', there are four peoples, of which Water, Earth and Fire remain. The three of them used to live in harmony with one another and with the Air Nomads, but the Fire Nation attacked everyone and [[FinalSolution exterminated the Air Nomads]].
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