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.
----
!!Examples:

[[foldercontrol]]

[[folder: Anime and Manga ]]

* ''Manga/{{Bleach}}'':
** The highest level of aristocracy in the Seireitei is held by the Four Great Noble Clans, only two of which have been revealed in the story (the Shihouin and Kuchiki Clans). The true extent of their power has never been fully revealed but they're indicated to even have ties to the Royal Realm. However, in the past, there actually used to be Five Great Noble Clans. The Shiba Clan was disgraced by mysterious events that still haven't been explained[[note]]According to the Turn Back the Pendulum arc, the Great Noble Clans had already been reduced to four, indicating that the disgrace occurred more than 109 years before the start of the story[[/note]]. The clan has been reduced to two known members, siblings living with the commoners in the Rukongai. [[spoiler: The Shiba clan is also found in the World of the Living as Isshin Kurosaki was the head of a minor branch of the Shiba clan and is the siblings' uncle. The family has also retained its connection to the Royal Realm despite being disgraced in Seireitei.]]
** An inversion. For most of the manga, the only known Quincies are the two surviving members of the Ishida family, Uryuu and Ryuuken, who refer to themselves as [[LastOfHisKind the last of their kind]]. In the final arc, [[spoiler:it turns out that the [[GoodIsOldFashioned Ishidas]] are the last of TheMissingFaction with the evil Vandenreich actually being ''the majority'' faction.]]
* ''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.

[[/folder]]

[[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.]]

[[/folder]]

[[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.

[[/folder]]

[[folder: Literature ]]

* Literature/TheBible has the Lost Ten Tribes of Israel.
** More specifically, these are the tribes that made up the Kingdom of Israel after a rebellion resulted in the Kingdom of Judea splitting off from it, following the death of King Solomon. The Kingdom of Israel was conquered by the Assyrians in 732 BC, and the people spread far and wide. The people of the Kingdom of Judea, which survived, managed to maintain cohesive Hebrew tradition and culture for the next 2.5 millennia despite being conquered and exiled several times, and so they got to name the other tribes as "missing". Today, many Ethiopean Jews (for example) consider themselves as -- and are often considered to be -- descendents of the Lost Tribes, and are being "reintegrated" into the modern Jewish culture. Many cultural and liturgical differences make clear the gaps that were left behind after so many centuries of dissociation.
* 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. In fact, several factions that previously had gone missing due to being pushed out by the current political balance have reemerged.
** The Black Court of vampires has been all but exterminated thanks to the helpful guide on killing them by [[{{Dracula}} Bram Stoker]]. This has made them the smallest and politically weakest faction, but its members are the strongest and smartest out of necessity.
* 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.

[[/folder]]

[[folder: Live Action TV ]]

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

[[/folder]]

[[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.

[[/folder]]

[[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 are surviving bloodlines of both Cappadocians and Salubri still extant, but they've fallen a long way from what they were.
** From ''TabletopGame/WerewolfTheApocalypse'', there are Apis [wereaurochs], Camazotz [werebats], and Grondr [wereboars], who were wiped out by the Garou [werewolves] during the Wars of Rage. Among the Hengeyokai (the shapeshifters of Asia), the Okuma--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/{{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 the Spider Clan]] can claim descend from him. The rest of the Children of Heavens don't seem to mind losing their brother.
* ''TabletopGame/{{Exalted}}'': Each original type of Exalt (and caste of [[{{Cyborg}} Alchemicals]]) have a magical material associated with them: [[MadeOfWin Solars]] with Orichalcum, [[BarbarianHero Lunars]] with Moonsilver, [[{{Ninja}} Sidereals]] with Starmetal, and [[ElementalPowers Dragon-Blooded]] with Jade. However, two of the existing magical materials don't have a 'proper' associated type of Exalts: [[AndIMustScream Soulsteel]] and Adamant. [[{{Necromancer}} Abyssals]] make good use of Soulsteel, but it's intimated they aren't quite what was anticipated for a Soulsteel-associated Exalt.
* ''BattleTech'': the Clans were descendants of [=SLDF=] which left the Inner Sphere with Kerensky centuries ago. While they're gone the IS has had four wars that bombarded their technology to the 20th century, and much old Star League tech was lost.
* The 2nd and 11th space marine legions in ''{{Warhammer 40000}}''. According to the fluff one or both was ordered destroyed by the Emperor for reasons not entirely specified, but some survivors were rolled into the Ultramarines. It's also been suggested that the reason one of the is missing is because they have the power to turn invisible and don't ''want'' to be found. There was also a lost Eldar Aspect Shrine, but as of 6th Edition it's been found again.
* ''TabletopGame/MagicTheGathering'': we got to see one of these ''become'' missing during Scars of Mirrodin, with no black-aligned Mirrans - no vampires and no moriok - surviving the Phyrexian assault as pure and free, because the black mana areas were the main focus of New Phyrexia's rise.

[[/folder]]

[[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). Half the colonists took to the shuttles, and landed on the planet Crete. The other half stuck with their damaged ship, reaching the planet Malta. They're now the most powerful pirate factions in the setting, the Corsairs and Outcasts respectively.
* 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 Kiithid. 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 [[spoiler:[[TomatoSurprise Kadeshi]]]].
* ''{{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.
* Both House Indoril and House Dres in ''VideoGame/TheElderScrollsIIIMorrowind'' are two of the five great powers of Dunmer society, but their presence is solely on the mainland and so they aren't seen in-game (Although Indoril is strongly associated with the in-game Temple faction, so while not formally present, their influence is still felt).
** House Dagoth applies historically, having been wiped out and demonized by the Tribunal as part of their effort to cover up the exact cause of Nerevar's death.
** In the second ''[[VideoGame/TheElderScrollsVSkyrim Skyrim]]'' expansion, it's revealed that this was the fate of, ironically, House [[spoiler:Hlaalu]], owing to their [[spoiler:strong support of the Empire]] getting them kicked off the Grand Council and turning them into scapegoats after [[spoiler: the Empire abandoned them during the Red Year and Argonian Invasion]].

[[/folder]]

[[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]].
----