!!Athar (Aka the Lost, the Defiers)
A faction dedicated to proving that the powers that rule the Outer Planes are not "gods" as they claim to be, but frauds who must be overthrown for the good of the multiverse. Their headquarters is the Shattered Temple in the Lower Ward. Their Factol prior to the Faction War is Terrance, a male planar human of LawfulGood alignment, who is a 19th level Priest of the Great Unknown. The Faction War sees Terrance Mazed by the Lady of Pain, and the Athar are forced to mostly quit the City of Doors to instead set up a new city for themselves at the base of the Spire, where the powers can't reach them. A few remain behind, hiding in the Undercity of Sigil.

* FireForgedFriends: They and the Godsmen were once enemies, until they figured out their ideas were NotSodifferent; they became close allies as a result.
* HollywoodAtheist: There is a strong vibe of this to the Athar.
** Their founders were Dunn (a man who wanted Poseidon to die because Poseidon and his church had taken all his possessions, his wife had been seduced into being a Poseidon priest's concubine, and his daughter had been stolen to Arborea by a proxy of Poseidon), and Ciro (a dispossessed Loki priest who wondered why gods, who should be beyond such things, would be [[GodNeedsPrayerBadly dependent upon the faith of others for their power]]).
** Meanwhile, their current factol became who he is when he realised that it was his own intellect and intuition that had helped him through every problem in his life, rather than the aid of his goddess, Mishkal.
** Athar tactics include a lot of stereotypical atheist tactics, like trying to LogicBomb priests or induce crises of faith.
* HonorBeforeReason: A disadvantage of being a member is that an Athar is not allowed to accept aid from clerics of specific deities; this includes healing magic, should the Athar be injured.
* NayTheist: With the minor twist that a portion of the faction are theists, believing in a (non-personified) Great Unknown. They just don't believe the 'gods' running around on the planes are ''real'' gods.

!!Believers of the Source (Aka the Godsmen)
A faction who believe that life is a series of tests and challenges that must be overcome; as a person incarnates, their actions cause them to move further up or down the ladder of being, until eventually they achieve godhood. Their main base of operations is the Great Foundry in the Lower Ward, from which the produce all of the metal goods of Sigil. Their Factol is Ambar Vergrove, a NeutralGood male planar half-elf, also a 19th level ranger. The Faction War results in Factol Vergrove being Mazed by the Lady, though many of his followers believe he Ascended instead. Forced to leave by the Lady's decrees, many Godsmen end up merging with the also-leaving Signers faction to form a new philosophy, known as the Mind's Eye, based on core elements of both the original faction philosophies.

* AscendToAHigherPlaneOfExistence: Their goal, kind of. Technically you can just ''walk'' to a higher plane of existence in Sigil, but they want to ''belong'' there as gods. (They also claim that the gods themselves are supposed to ascend as well eventually; it's kind of like Nirvana.)
* EternalEngine: The Great Foundry is like this, although it is unique among the Trope in that it does have a very necessary use. (It makes all metal goods for Sigil except weapons and armor.)
* SecretTestOfCharacter: They believe every being in existence is being tested. They aren't quite sure what the tests are (like whether they have to be Good, Evil, Lawful, Chaotic, or whether it's something else) but they try to figure that out.

!!Bleak Cabal (aka Bleakers)
An ancient faction, defined primarily by their belief in the utter lack of any great meaning or hidden purpose to TheMultiverse. Their role in the Cage is predominantly one of charity and compassion; they operate free soup kitchens, run orphanages, and take care of the mentally ill from their headquarters in the Gatehouse, an ominous structure at the edge of the Hive Ward. Their Factol is the ChaoticNeutral male planar half-orc Lhar, an 8th level fighter whose parents (a blind male human and a female orc) moved to Sigil in hopes that their InterspeciesRomance would be tolerated better there; unfortunately, they found it difficult to get jobs and eventually had no choice but to give Lhar to the Bleaker orphanage. At the time of the Faction War, Lahr had already consigned himself to the Madhouse, having been replaced by Sruce, who is sent to the mazes. The Bleakers are unaffected by the events that plot; they simply shrug their shoulders, stop calling themselves a faction, and keep on as they were before.

* TheAntiNihilist: the good aligned members anyway.
* BedlamHouse: The Gatehouse has been known to end up like this at times, depending on who is currently in charge of the Bleakers.
* DarkIsNotEvil: They officially believe the multiverse is meaningless and pointless, with there being no great purpose to anything, but they are mostly not of evil alignments and, indeed, dedicate themselves to charity and good works -- if there is no point, then there is no reason not to try and alleviate the suffering of others, is there?
* DeterminedDefeatist: What keeps Bleakers going as individuals instead of succumbing to apathy and dying; there is no point to anything they do, but they have to keep trying.

!!Doomguard (aka Sinkers)
A faction who worships entropy, believing that all things will inevitably end and it is only proper to celebrate the destruction that awaits all. They control the Armory, the great storehouse of all weapons in Sigil located at the edge between the Lady's War and the Lower Ward, and thusly serve as a restraint on the war capabilities of the Harmonium. Their Factol is Pentar, a ChaoticNeutral female planar human, 20th level ranger, who actively encourages the Doomguard to be active in furthering entropy, driving the majority who violently lash out against the multiverse to drive them to destruction. Wielder of the Blade of Modron Death, she has less interest in her faction and more in planning for her own upcoming attempt to destroy the next Great Modron March. Factol Pentar was one of the first Factols to be Mazed during the Faction War, and the subsequent battles see the Doomguard rendered virtually extinct; those who survive are hated by the populace of Sigil with almost as much intensity as the members of the Mercykillers and Fated. The survivors flee to their fortresses on the Negative Quasielemental Planes, but because of their ethos they seem likely to fade away into oblivion.

* DarkIsNotEvil: The Doomguard may not have the nicest sounding goal, but there are members of all ethical alignments and even some Good aligned member.
** DarkIsEvil: However, the faction of the Doomguard advocating direct violence and destruction ''is'' in the majority of the faction, and their leader is part of this faction.
* OmnicidalManiac: As mentioned, there are Doomguards who actively believe entropy needs a helping hand in the total consumption of everything, and so try to speed it along.
* StrawNihilist: A rare variant where they believe the active pursuit of universal annihilation is a worthy pursuit in its own right.

!!Dustmen (aka the Dead)
A faction that believe all life and afterlife as seen in the Great Wheel is a falsehood; instead, all who think they are alive are instead dead souls, trapped in a false perception of life. Only by letting go of this misconception and becoming detached from the lie can they fall into True Death, and whatever passes beyond. As a consequence, they operate the Mortuary in the Hive Ward and make themselves useful by collecting and disposing of all the many corpses that Sigil generates every day. Their Factol is Skall, a NeutralEvil male planar lich of unknown origin, and a 19th level wizard. The Faction War sees the Dustmen dissolved as an official faction, but they retain their role as the gravekeepers of Sigil, even if their philosophy starts to wither out with the Mazing of Skall, whom is believed by the Dustmen to have officially ascended to True Death at last.

* TheCoroner: When in charge of the Mortuary, they were in charge of collecting, processing, and disposing of Sigil's dead, along with everything else that entailed. Given the high population density of Sigil, there's no space for cemeteries, the Mortuary having portals to every known Prime world. The Dustmen would typically send a corpse to wherever the next of kin desired; unclaimed ones would be cremated via portals to the Elemental Plane of Fire.
* DarkIsNotEvil: Officially, the Dusties lean towards the neutral and lawful scale of the alignment axis, and they do contribute a vital role to the running of Sigil. Still, as is lampshaded in "The Factol's Manifesto" sourcebook, for all that it's well-meant, most people tend to view somebody who hopes for the demise of everyone else to be evil.
** DarkIsEvil: Then again, there are a ''lot'' of NeutralEvil and LawfulEvil Dustmen, and their Factol is not only NeutralEvil himself, he plans to force his philosophy upon the multiverse and help all achieve True Death... ''by exterminating all life in'' '''TheMultiverse''' ''with an army of undead slaves''.
* DeadAllAlong: The central dogma of their philosophy; they think ''everyone'' is dead. Some are just more so than others.
* NatureHero: Oddly enough, a lot of Druids are members. Dustmen Druids see death as a necessity in the Circle of Life analogy.
* TheNecromancer: A lot of necromancers are part of the Dustmen. The Dusties also use large numbers of walking dead (animated skeletons and zombies) as manual labourers, and, two of the five "Circles" (ranks in the Dustmen hierarchy) are actually comprised solely of free-willed undead.
* NightmareFuelStationAttendant: Some Dustmen are good, some are evil, but almost all of them are ''creepy''. To give one of many examples, ''In the Cage: A Guide to Sigil'' mentions a member named Mhasha Zakk, who runs a taxidermy shop in the Merchant's Ward, who acts like a sweet old granny save for the fact she ''really'' loves her work, and if a customer is an attractive type, she might ask for his or her corpse after his death. And she is deadly serious about it. What makes this especially creepy is the fact that at least three customers apparently accepted this offer - they are displayed in her shop.
* SecretCircleOfSecrets: The higher ranks of the Dustmen are similar to this. Even amongst the Dusties themselves, few people know that the Third and Second Circles are comprised exclusively of Dustmen killed and reanimated as undead by Skall himself.
* TheStoic: Encouraged as a way to avoid attachment.
* ThouShaltNotKill: Amazingly, the Dustmen try to avoid killing people through violence if they can. They believe that only via ''natural'' death can mortals find true enlightenment. (This does not mean, however, that all of them are pacifists that will not fight and will automatically grant mercy to enemies.)

!!Fated (aka Takers, The Heartless)
A faction dedicated to the idea of taking what you want from those you can take it from. They serve Sigil in the role of its tax collectors, operating out of the Hall of Records. Their Factol is a male prime human from [[TabletopGame/{{Greyhawk}} Oerth]] (though he claims to have been born on [[ForgottenRealms Toril]]) named Rowan Darkwood, a ChaoticGood epically powerful individual (he's a dual-classed ranger/priest of Heimdall, with 19 levels in the former class and 20 in the latter class). The Fated earn great hatred because it is Factol Darkwood who sparks the Faction War. They are forced to flee the Cage and settle on Ysgard, eventually evolving into an arguably purer incarnation of their philosophy that focuses on taking what they ''need'' and not what they ''want''.

* AmbitionIsEvil: Beyond the fact that the Takers can basically be seen as this themselves, Rowan Darkwood's ambition leads this officially ChaoticGood man to commit atrocities that include seducing a mentally ill girl young enough to be his daughter, marrying her for power, [[BreadEggsMilkSquick selling her into slavery to the Fiends]], and then sparking the infamous Faction War.
* GoodIsNotNice: Whilst LawfulGood characters cannot join the Takers, but there are more than a few NeutralGood and ChaoticGood Takers.
* HonorBeforeReason: A Taker cannot accept anything that he did not take for himself. This includes genuinely offered aid from others; a member of the Fated cannot even allow another person to heal him if he's injured.
* IOwnThisTown: The Fated were in charge of collecting taxes, potentially making Darkwood the most powerful individual in Sigil other than the Lady. His downfall was not settling for second-best.
* MightMakesRight: The fundamental core of their philosophy; take what you can, and to the hells with everybody else.
* TheScapegoat: As one might expect, the members who survived the Faction War are ''not'' well-liked, and pretty much everyone else blames them for what happened. seeing as Darkwood started the whole thing.
* SocialDarwinist: They may believe in MightMakesRight, but they aren't hypocrites about it; if you're strong enough to take what you want from a Fated, and proceed to do so, then it belongs to you and they just have to get stronger. Life is about the struggle to get stronger, and the weak deserve no pity or aid.
* StableTimeLoop: The eventual fate of Factol Darkwood. In short, he starts the Faction War with the intent of using it to cover his efforts to obtain the Labyrinth Stone and use it to cast the Sigil spell and claim control of Sigil. He promptly gets Mazed by the Lady on day 19. Eventually, he escapes, only to find the Maze has released him into Sigil some 500 years into the past. This version of Darkwood is imprisoned by the Bleakers as a barmy and renamed Gifad. Towards the end of the Faction War, Gifad is released or escapes and is used to try and end the Faction War by casting the Sigil spell with the aide of the Labyrinth Stone. He fails and is cast into the past, over 10000 years ago. Having lost his memory, he studies magic and eventually becomes the wizard who created the Labyrinth Stone and the Sigil spell in the first place -- only to be sealed inside the Stone when he attempts to cast it. And then, millennia later, Rowan Darkwood will be born, learn of the Stone and the spell, and begin the Faction War all over again.

!!Fraternity of Order (aka Guvners)
A faction dedicated to the belief that all things in the multiverse are governed by laws and if these laws are uncovered, one can control reality itself. They form the trinity of justice in Sigil with the aid of the Harmonium and the Mercykillers; the Guvners create and define the laws, as well as try criminals, while the Hardheads catch the crooks and the Red Death punish them. As a result, their faction headquarters is the City Court, at the heart of the Lady's Ward. Their Factol is Hashkar, a male planar dwarf Sage of LawfulNeutral alignment. Unbeknownst to almost anyone outside the highest Guvners (except the Revolutionary League -- and even they don't really know (or much care) that it's true), Hashkar is actually a petitioner to The Lady. According to the story Hashkar was once a planar dwarf who came to revere the Lady of Pain as the law at the center of the multiverse. He has never left Sigil, even for the faction HQ on Mechanus. And his single-minded dedication to law makes him have a personality just like that of a petitioner. It is possible that the Lady allows him to worship her in secret, but if that were to come out she'd have to kill him as an example. He is murdered by a Xaositect assassin during the Faction War; this leads the Fraternity to declare war on the Xaositects as a whole. After the Lady of Pain makes her decree, they retreat en-mass from Sigil to their headquarters on Mechanus, to begin the laborous process of electing a new Factol and restructuring themselves to return to Sigil.

* AwesomenessByAnalysis: What they hope to achieve.
* CorruptBureaucrat[=/=]ObstructiveBureaucrat: Common negative stereotypes of Guvners, and one that evil-aligned Guvners tend to easily fit into.
* InsufferableGenius: A common trait amongst the Guvners. For example, they almost never allow for appeals against their sentences -- after all, they know all the rules, so if a Guvner made a ruling, then it must obviously be the right one.
* OrderVsChaos: Firmly on the "Order" side of things; all members of the Fraternity of Order ''must'' be Lawful, though whether they are LawfulGood, LawfulNeutral or LawfulEvil is unimportant.
* LoopholeAbuse: Some of them can actually manifest powers by exploiting loopholes in ''the laws of the universe itself''. (In game terms, learning how to do this is a benefit of being a member; however, you can only use a power like this [[AwesomeButTemporary a limited number of times]] before the loophole closes.)
* MotorMouth: Their former leader, the now-deceased Factol Haskar, was notorious for this. It was unwise to ask him a question (even one as simple as "Which way to the exit?") unless you planned on listening to him for a ''long'' time. Haskar tended to lecture at the drop of a hat, and would always answer questions in the most complete and thorough ways possible.
* RefugeInAudacity: The Guvners openly admit that they seek to know the rules so they can bend them in their favor, with the eventual goal of doing this to the rules that hold reality itself together. People let them do it anyway, simply because they're the only guys who really know how everything works now.
* RulesLawyer: The Fraternity of Order is basically what happens when these kinds of people unite to try and take over the universe.
* VastBureaucracy: What the Fraternity is like, and what any place controlled by them or where they are drawn to tends to be.

!!Free League (aka Indepts)
Aka "the Faction that isn't", the Indeps are the loosely aligned coalition of independent Sigil natives who, for whatever reason, refuse to join one of the other factions. They are defined, as far as that term can be applies to them, by their belief in and promotion of acceptance, balance and individuality. This means the majority of Indeps are Neutral in some way -- TrueNeutral, NeutralGood or NeutralEvil, typically, with True Neutrals and Neutral Goods being most common. The Free League is regarded with disdain but usually indifference by most "Order-focused" Factions; the Harmonium are a hostile exception. Because of their loose nature, they have no official Factol, though there are three individuals respected enough to be "unofficial leaders"; Bria Tomay (planar female human, 14th level ChaoticNeutral bard) and the twins Lethea & Lesander (female and male, respectively, prime wemics, 6th level LawfulNeutral fighters). All three of them are Mazed during the Faction War, though the Free League, understandably, accuses the Harmonium of having them murdered. The ending of the Factions is no sweat for the Free League, who simply repeat that they are not a faction and get down to enjoying life without the Harmonium oppressing them.

* AnarchyIsChaos: Averted. They get along just fine without a Factol.
* BlessedWithSuck: Of all the Factions, they are the only one that can be said to have the actual attention of the Lady of Pain upon them. ''This is not a good thing''.
** To put it in proper perspective; right after the Great Upheaval, when the Factions were reorganised into the 15 seen here, the Free League swelled to over one million members. The Lady, annoyed by the fact that one of the least tractable/manipulatable Factions was now so strong, promptly took action; over the span of 50 years, she personally winnowed the membership down to under 20000 souls by means of Mazing or eviscerating whoever caught her attention.
** At the time that "The Factol's Manifesto" was written, her amusement at the fact that Indep historians were attributing the mass culling to a mysterious plague led her to ''create'' that plague to infect the Indeps at random.
* YourTerroristsAreOurFreedomFighters: This more or less sums up the relationship between the Harmonium and the Free League.

!!Harmonium (aka Hardheads)
A faction originating out of a Prime world called Ortho, founded around the ideal of bringing about the greatest good for the greatest number. No matter what it takes or if others like that. A fairly young faction, only 500 years old at the time of Planescape's initial release, they began when a group of adventurers set out to "rid the country of chaos and bring peace to the land". Somehow, they went from succeeding at their goal to leading a righteous crusade to extend the same peace and harmony over the rest of Ortho, until all non-Lawfuls had been eradicated. Disturbed by the fact that chaos and disorder would still plague their lawful, regimented society, the Harmonium turned its attention to what it believed was the source; the Outer Planes. After an initial crusade to the Lower Planes failed, they resettled in Sigil as a "beachhead" in their conquest, and have since made themselves useful. Allies to the Fraternity of Order (who form the court system) and the Mercykillers (who punish the guilty), the Harmonium have become the police officers of the Cage, operating out of the City Barracks in the Lady's Ward. Their Factol is Sarin, a male human [[LawfulGood Paladin]] (16th level) from Ortho, who is married to Faith, a LawfulGood 12th level cleric and a female planar human. During the Faction War, Sarin is assassinated by the Revolutionary League, who publicly take responsibility, and his widow takes over; it is her benevolent commands that persuades them to leave peacefully and retreat to Arcadia, where there are signs that the group will become less militaristic. Few hold any belief that the change will be permanent, though.

* CityGuards: Of Sigil, before the Faction War.
* GoodIsNotNice: The Harmonium's intentions and overall goal ''are'' benevolent, but their actions in pursuit of it... well, see below.
** To put this into perspective; if the Factol finds out about the LawfulEvil Hardheads who have been murdering Indeps, they will be chastised... but only for doing so without proper orders; the Harmonium expects to one day officially crack down upon the Free League, so their actions would have been fine if they hadn't been acting independently.
* KnightTemplar: A big part of why the Harmonium is so disliked by everyone, despite their good intentions. The Harmonium ''will'' bring peace and order to the universe -- by force, if need be.
** Their homeworld of Ortho has had all Chaotic and even Neutral races completely wiped out in pursuit of the Harmonium's "perfection". This ''includes'' ChaoticGood and NeutralGood races like elves and pixies.
** They're so bad about this that their former headquarters on Nemausus generated so much evil in the name of good that it turned the plane's CharacterAlignment into LawfulNeutral[[invoked]] dumping it from Arcadia into Mechanus.
* NeverLiveItDown: InUniverse. The Harmonium's accidental planar slip of Nemausus, the third layer of Arcadia, is a ''big'' thumb in the eye to the faction's goals, abilities and beliefs.
** People often aren't too impressed with the Harmonium when they find out about the whole "genocide of ChaoticGood and NeutralGood races on Ortho" thing.
** In "The Factol's Manifesto", it's mentioned that those who are familiar with Rajaat and his Champions from [[TabletopGame/DarkSun Athas]] have been known to directly compare the Hardheads to them -- something the Harmonium vigorously protests against.
* OrderVsChaos: The Harmonium stands on the "Order" side and is allied with the similarly Order-focused Fraternity of Order and Mercykillers, whilst it remains bitter enemies with the Chaos-focused Free League, Revolutionary League, Xaositects, Fated and Doomguard. They also don't like the Bleakers much.
** Lawful alignment is essential to joining the Hardheads.
* [[PatronSaint Parton Deity]]: Most of them regard the Oeridian god of justice St. Cuthbert as their patron; he is worshipped by most spiritual leaders within the faction.
* FromNobodyToNightmare: According to legend, they started as nothing more than a RagtagBunchOfMisfits, like the typical adventuring party. They grew into an ArmyOfThievesAndWhores, then a well-disciplined army, and eventually, an army of such great size that they brought order and peace (or their perception of it) to Orthos. (But then they figured, why stop there?)
* WellIntentionedExtremist: Despite the bad reputation they have achieved, the Harmonium keeps attracting LawfulGood types, who believe that their cause is worthy even despite how they attempt to bring it about.

!!Mercykillers (aka The Red Death)
A faction dedicated to the pursuit of justice above all else, born from the union of two similar factions at the end of the Great Upheaval; the LawfulGood Sons of Mercy and the LawfulEvil Sodkillers. The Faction War sees them split back into these two factions again, for the most part.

* FluffyTamer: Their mascot is a wyvern called the Wyrm, which was kept in a tower near the Prison. Mostly it's a pet, but it did have uses; first of all, the worst criminals that received the death penalty (usually for betraying the city) were fed to the Wyrm. Second, its venom could be made into TruthSerums, making interrogations incredibly easy.
* TheDeterminator: If you break the law, they ''will'' find you.
* TheFettered: Mercykillers officially cannot act to punish injustice until and unless the criminal is properly defined as such. In the triad of lawmaker factions, the Harmonium catches the criminals, the Fraternity of Order convict them, and the Mercykillers punish them. Mercykiller players are forbidden from catching or judging enemies of their own initiative, as a result; the best they can usually do is note down injustices in order to present them to their faction and get them avenged as soon as possible. (Of course, one reason the crime rate around the Prison is almost zero was due to too many rumors of them breaking that rule.)
* KnightTemplar: Only MUCH more so then the Harmonium; the LawfulEvil side of the Mercykillers holds far more sway over the faction than it does in the Harmonium.
* LawfulNeutral[[invoked]]: This is the ideal alignment that the Mercykillers aspire towards, to the extent that LawfulGood and LawfulEvil Mercykillers are prone to suffering penalties to their faction abilities due to the conflict between their viewpoint and the ideals of the faction.

!!Revolutionary League (aka Anarchists)
An extremely loose faction based pretty much entirely on the idea of opposing the other factions.

* AndThenWhat: All of them want to bring down "The System". Exactly what they intend to build in its place is a matter of debate.
** [[BeCarefulWhatYouWishFor In a sense, they got exactly what they wanted at the end of the Faction War]]: all the factions, even theirs, were gone as the major players in Sigil. What they should do next is a matter of hot debate between the various cells of the faction.
* BombThrowingAnarchist

!!Sign of One (aka Signers)
A faction who believe that a person's willpower defines reality around them.

* ClapYourHandsIfYouBelieve: A solipsistic variant.
* ItsAllAboutMe: This is literally the central belief of all members, but funnily enough not all of them are jerks.
* {{Narcissist}}: This is a group that claims one person is the center of the universe, and while they are at a loss to reveal who, they are certain this person is a Signer. As a result, they come across as this.
* RetGone: It has not been proven, but many detractors claim they can (and have) made some of their opposition disappear from existence simply by willing it. (Of course, if it ''is'' true, it seems unusual for a detractor to say this and thus confirm their claims.)

!!Society of Sensation (aka Sensates)
A faction who believe that the multiverse only exists insofar as you can experience; thus, by experiencing all the multiverse has to offer, you will understand the true purpose behind existence.

* TheHedonist: Some Sensates are this, but they are looked down upon by most true Sensates and quietly pushed out of the way.
* SenseFreak

!!Transcendant Order (aka Ciphers)
A faction believing that instinct is superior to thought and so the body must be trained to act without conscious thought in order to achieve true transcendence.

* DontThinkFeel: All members of the Faction must act on their first impulse.
* KarmaHoudini: While very little of the responsibility for the Faction War falls on them, they were virtually untouched and unpunished for it. While no longer an organization with an official charter, former members still run the Great Gymnasium, unofficially spreading their ideals through the Cage and the Planes, while Rhys was the only Factol not killed or sent to the Mazes during the War, and is now a member of Sigil's city council.
* LeeroyJenkins: Well, not exactly, but their philosophy gives a Player Character who joins a rather unique penalty: once he has decided on an action, he is not allowed to change his mind. (In other words, this is where a "no takebacks" rule is mandatory for a player). This does not mean the Player will always become a Leeroy Jenkins, but it might increase the risk or it happening.

!!Xaositects (aka Chaosmen)
A faction that exists on the idea that the multiverse is nothing but chaotic whimsy and chance, so the true way to experience life is to give yourself over to whim and chaos.

* ChaoticStupid: Not technically necessary, but there is a tendency for people to play the faction this way. Probably because the descriptions of the faction tend to make them sound like they ''are'' this way.

The outsiders native to Mechanus, the LawfulNeutral plane, who originate from their segment of the gear-world known as Regulus. The Modrons are a bizarre hierarchy of construct-like beings, starting at the barely-sentient Monodrone and ascending all the way to the godlike Primus, the One and the Prime.

* {{Clockwork Creature}}s: Subverted; they ''look'' like machines, and are made of metal, but they're very much living creatures. (Which means, for instance, spells that only work on living beings, like healing potions, work on them just fine.)
* HiveMind: Sort of. Modrons are in a sense, extensions of Primus, a godlike being whose own thoughts direct and move the whole race.
* LawfulStupid: As elemental incarnations of the LawfulNeutral CharacterAlignment, Modrons are lawful to the extent that it makes them seem quite insane to human perspectives. To put this in perspective; during the second adventure of "The Great Modron March", the players have to deal with the fact that the Modrons refuse to accept that a city in their way has changed in the three centuries since the last march and so will blithely march their way through the city, smashing buildings that are in their path and trampling any living creature that fails to get out of the way.
* LivingPolyhedron

The outsiders native to Limbo, the ChaoticNeutral plane.

* ChaoticStupid: As elemental incarnations of the ChaoticNeutral CharacterAlignment, Slaadi are chaotic to the extent that it makes them seem quite insane to human perspectives.
* ExtremeOmnivore: As "chaos elementals", Slaadi will eat just about anything that catches their eyes.
* RealityWarper: They have the ability to shape the essence of Limbo to a degree proportionate to their intelligence; mortals can learn how to do this, but slaadi do it by instinct.

!! Yugoloths
The third branch of the fiend family, the daemons to the tanar'ri (demons) and baatezu (devils). Lords of Gehenna, the NeutralEvil with a hint of Lawful plane, although they originated in the Grey Waste, the pure NeutralEvil plane.

* AuthorityEqualsAsskicking: Subverted. The lowest ranking Yugoloth is actually stronger than the next rank. Those who realize this get singled out as potential candidates for promotion.
* EvilTowerOfOminousness: They have two of these, the Tower of the Arcanaloths on Gehenna, and the much larger Khin-Oin on the Grey Waste. Attempts have been made to build a third tower on Carceri, but the geheleths keep tearing it down.
* {{Hermaphrodite}}: According to the "Faces of Evil: The Fiends" sourcebook, yugoloths are all either hermaphroditic or genderless, in terms of reproductive capability, adopting genders pretty much according to their whim.
* NoMouth: The highest ranking Yugoloths, the Ultroloths, don't have mouths.
* PlagueMaster: The Oinoloth (the powerful Yugoloth that currently rules the tower of Khin-Oin) can control the plagues of the Grey Waste.
* {{Precursors}}: Legends tell of the baernoloths, ancient fiends who created the yugoloths, and also purged Law and Chaos from themselves by transferring it into larvae which became the first baatezu and tanar'ri. Of course, while the baernoloths clearly do exist (one of them plays a vital role in one module) almost all legends about them are told by the yugoloths, and thus [[UnreliableNarrator subject to scrutiny.]]
* WarForFunAndProfit: Some believe that they are behind the Blood War.

[[folder:Specific [=NPCs=]]]
!!A'kin the Friendly Fiend
A cheerful and apparently good-natured male arcanoloth who runs a magic item shop known as the Friendly Fiend.

* AscendedDemon: Seemingly. [[GenreSavvy No Cager really buys it, however]].
* BazaarOfTheBizarre: The store he runs is like this. (Surprisingly, many powerful magical items used by Shemeshka have come from here.
* NobleFugitive: Fugitive, definitely. He became one by writing ''The Factol's Manifesto''. He claimed to have only good intentions in mind, to expose the corruption of the factions, but the faction leaders thought otherwise.
* TheRival: To Shemeshka, but to what extent is not known; they may be [[FriendlyEnemy Friendly Enemies]], [[ArchEnemy Arch Enemies]], somewhere in between, or may even shift between the two. What is known is, despite their apparent enmity, they seem to cooperate at times, many of the powerful magical items Shemeshka uses coming from A'kin's store. The biggest indication was in the forward to ''The Factol's Manifesto'', where A'kin (although he didn't reveal himself then) said that Shemeshka and her organization was his biggest source of information for the book, but she eventually double-crossed him and leaked an advance copy to the Mercykillers, thus making him a fugitive.

A mysterious "fallen Dabus", supposedly disowned by the Lady of Pain for becoming a priest of the dead god Aoskar -- indeed, it's commonly whispered that it was his conversion to Aoskar that prompted the Lady to move against him and destroy him. He now runs a tattoo business and is a member of the Sign of One faction.

* BrokenAngel: He's a fallen Dabus, disowned by the Lady of Pain, unable to float.
* DoomMagnet: Not really, but most residents of Sigil are ''afraid'' he might turn into one. After all, he double-crossed the Lady, and it's very possible she might just be biding her time. People tend to avoid him, not wanting to be around if she ever does come to punish him more severely.
* RealityWarper: On a limited scale. Occasionally, the tattoos he creates with his rebus speak become real items or even creatures (with limited duration). He has very limited control over this, and it more often than not happens unintentionally.
* StarfishLanguage: Like all Dabus, he speaks in a visual language of rebus puzzles. Fortunately, a helpful customer who frequented his tattoo parlor often put together a guide for understanding the language of the Dabus, which he sells there too.

!!Shemeshka the Marauder
A female (or is she?) arcanoloth/ravaasta (in 4e) who is infamous throughout Sigil for being a fabulously wealthy business owner ''and'' the master of the biggest and best guild of spies, thieves and assassins in all the Cage, a position that has earned her the title "King of the Crosstrade".

* AmbiguousGender: Dresses, acts like, calls "herself" and is referred to as a female... but her profile writeup in the "Uncaged: Faces of Sigil" sourcebook officially lists her gender with a male symbol. Later works, however, use a female symbol. Not helped by the fact that all yugoloths are {{hermaphrodite}}s, according to the "Faces of Evil: The Fiends" sourcebook.
* BerserkButton: Her temper is infamously volatile, but the surest ways to tick her off? Ask why she doesn't call herself "Queen of the Crosstrade", or mention A'kin the Friendly Fiend.
* BitchInSheepsClothing: IncrediblyLamePun aside (arcanoloths look like [[PettingZooPeople anthropomorphic jackals]], ravaasta look like equally anthropomorphic foxes), as sweet, friendly and generally affable as she acts, Shemeshka is still a highly dangerous fiend and, more importantly, has a savage temper that is easily unleashed.
* EnsembleDarkhorse: Of the [=NPCs=] of Planescape, she may easily be one of the best known, besides the Lady of Pain herself. When the 4th edition "Manual of the Planes" sourcebook was released, Shemeshka was one of the very few Planescape [=NPCs=] to make the edition jump. Indeed, one could argue that the Arcanoloths survived the transition and became the Ravaastas mainly due to her impact on Planescape.
* FlipFlopOfGod: Whether or not Shemeshka is a transwoman or a ciswoman; as mentioned, "Uncaged" says she is male, while other sourcebooks say she is female. "Faces of Evil", meanwhile, pretty much makes it canon that it's all up to what she considers herself to be, since as an arcanoloth she's biologically hermaphroditic.
* HairTriggerTemper: Shemeshka's temper, and the spontaneity with which she'll fly into a berserk rage, is infamous throughout Sigil.
* InterspeciesRomance: It's a common rumor that the reason Shemeshka hasn't moved against her would-be rival, the tiefling Kylie, is because she gave birth to her after a liason with a human man.
* MamaBear: If Kyle truly is her daughter, the Trope applies; hurting her is off limits if Shemeshka has anything to say about it. As Autochron the Bellringer discovered, Kyle seems be under Shemeshka's protection.
* SheIsTheKing: Shemeshka is ''always'' referred to as the King of the Crosstrade -- and don't you forget it!
* SissyVillain: Whether or not you believe she's male, Shemeshka is still very flamboyant and effeminate. She iconically favors wearing a dress made of thousands of small blue/green/violet beads, and she adorns herself with beads, jewellery, bracelets and rings to the point of garishness, as others have noted (but rarely commented on). She's also incredibly vain and fussy about her grooming; she always has to be meticulously beautiful and she surrounds herself with "groomer-guards", one of whom carries a full-length mirror and the rest of whom have the main responsibility of keeping her immaculately clean and beautiful, at all times.
** Of course, the groomer-guards are also [[BattleButler her most deadly assassins and serve as bodyguards]], whilst the mirror is a powerful magical item (a "Mirror of Mental Prowess") that enables her to scry people even across the boundary of planes, teleport to any place she is scrying, read thoughts and perform divinations. (The one in charge of holding the mirror, Colcook, is the servant who's worked for her the longest, and the one she trusts the most. [[spoiler:Unbeknownst to her he's actually Jemorile the Exile in disguise, [[TheChessmaster the rilmani]] who is assigned to Sigil.]]
* {{Transsexual}}: It's obscured by time, and canonically dubious (see FlipflopOfGod) but, a fan willing to track down the 2nd edition "Uncaged: Faces of Sigil" sourcebook will discover that Shemeshka the Marauder is actually male. She just looks like a woman, dresses like a woman, and insists on being referred to by feminine pronouns.
* UnknownRival: While she becomes enraged if someone mentions A'kin in her presence, no-one ''dares'' mention Zadara, a titan and member of the Merkants who Shemeshka hates not only because her financial and business connections give her more influence in Sigil, but because Zadara is a more influential ''female'' resident. (Of course, the ''most'' influential female resident is the Lady herself, but no-one ever points that out to Shemeshka.) It's unlikely Shemeshka will ever try to make a move against Zadara, though; Zadara ''is'' a titan, who killed ''two'' pit fiends who invaded her house, personally. (There are witnesses to back this up.)
* WhipItGood: When angry or actually attacked, Shemeshka's preferred weapon is to break off a vine from her razorvine headdress and use it as a lethally barbed whip.