The following is a list of various organizations, establishments, institutions and societies present in source book canon. It does not include server canon, fanon, homebrew or anything else otherwise not readily available with clever use of google and key words.
BAROVIA
Dawnslayers - Morninglord-loyal knighthood of vampire hunters.
Crimson Hounds - Elite enforcers of the Von Zarovich bloodline. Known to put whole villages to the sword to teach a specific point.
Tyrant Mages - Von Zarovich family mage elite and secret police. Known for their cruelty.
Keepers of the Black Feather - Secretive Barovian lodge that wages an unceasing shadow war against the creatures of the night.
Order of the Guardians - A monastic order of lorekeepers dedicated to finding cursed objects and keeping them out of the wrong hands.
Gundarkite Rebels - Organized resistance to outside rule of Gundarkite territory.
Red Vardo Traders - Band of salvagers and thieves who 'return' items to their 'original owners'.
Ba'al Verzi - Infamous fraternity of assassins.
Church of Ezra - No firm foothold in establishing wide belief. Seen as Borcan poisoners and agents.
Church of Hala - Presence in Bstobis. Regarded as helpful and unobtrusive, mostly left to their own devices.
Cult of the Morninglord - Most popular religion in Barovia. Large Gundarakite following which tends to cause suspicion.
Cult of Nerull/Erlin - Marginal presence, small numbers of Gundarakites associate Nerull with ethnic pride. Underground following.
BORCA
Boristi Trading House - A major merchant interest, led by the Boristi family of Borca.
1st Sect of Ezra - LN "Home Faith" centered in the Great Cathedral of Levkarest. Almost all Borcans worship/pay lip services to Ezra. Powerful church base.
The Scions of Yakov Dilisnya - Secret society in the church of Ezra, dedicated to creating an empire using the influence and power of the Ezrite church.
Dilisnya Crime Family - One of the most potent criminal organizations in Ravenloft, led by Ivan Dilisnya.
Church of Hala - Small following in the rural areas of Borca. Often used as scapegoats as witches.
Academy of Style - Expensive and prestigious finishing school in Levkarest open only to the most respected families.
DARKON
4th Sect of Ezra - LE "Zealots" branch of the faith centered in Nevuchar Springs. Militant and steadily growing in popularity for its beliefs in fighting the darkness.
The Kargat - Secret police dedicated to furthering the will of Azalin Rex. Membership all monstrous.
The Unholy Order of the Grave - A nightmarish society of monsters who literally worship death.
Dark Delvers - Mystery cult centered in Darkon, searching for truth about the Hated Mother and her power.
Brautslava Institute - Teaches various arcane-related subjects
The Fraternity of Shadows - An arcane cabal (Illusionists) of researchers and scholars who seek to know the truth behind Ravenloft and control it. Based in Brautslava.
The Order of the Guardians - A monastic order of lorekeepers dedicated to finding cursed objects and keeping them out of the wrong hands.
University of Il Aulk - Once the greatest school on the Core, now a crumbling ruin in the dead city.
The Eternal Order - Offically sanctioned cult of the dead though heavily diminished over time. Churches are largely autonomous from each other.
Cult of the Overseer - Popular in the west, heavy message of compassion, charity and the need to do good deeds while one lives to be judged favourably in death.
DEMENTLIEU
3rd Sect of Ezra - TN "Erudites" centered in Ste. Mere des Larmes in Port-a-Lucine. Largely unconcerned with gaining new followers, has a tolerant mindset to other faiths.
Van Richten Society - A loose alliance of correspondents who seek to continue Van Richten's legacy.
Les Ordures - A group of lower class men and woman seeking to strike out at the nobility through embarrassment and belittlement.
La Societe de Legerdemain - An organization of street performers who provide the means to study real magic.
Noble Brotherhood of Assassins - Organization of social intriguers that works to bring down the most corrupt nobles in Dementlieu.
L'Academie des Sciences - Dementlieu based cabal of mystics who seek to recover and study magical items.
The Brain - An underground crime and resistance network fighting against Dominic D'Honaire, led by Rudolph von Aubrecker, the Living Brain.
University of Dementlieu - The current prominent university in the Core.
Church of Hala - Maintains several hospices, well received by the lower class and treated with indifference by the nobility.
Echanson's Heresy - Cupbearers who believe Ezra was born as a mortal, scour the realms in search of her secret descendants.
Circle Sinister - Crime racket that's a major player in Port-a-Lucine underworld. Led by Black Pieter, often noted for his willingness to work with adventurers if it benefits him.
FALKOVNIA
The Talons - Fanatical "knighthood", the best soldiers in Falkovnia who are absolutely loyal to Drakov. Each member is altered via dire ritual including the consumption of a form altering potion and is practically a terminal psychotic.
Freemen of Falkovnia - The only rebel group of Falkovnians that's managed to survive for more than a week.
Ebon Fold - Secret society of assassins operating in Falkovnia at Azalin's behest. Membership formed from the reanimated corpses of impalement victims.
Church of Hala - Conforms to Falkovnian ideals of religion so left to its own devices, hospices seem to always meet with bad luck and hasty demises though.
Church of Ezra - Under heavy scrutiny, acolytes regularly tortured and killed for aiding abetting resistance movements.
Eternal Order - Appeals to veteran soldiers and seeks largely to appease Darkon's restless dead to prevent them from swarming the border.
Stagengrad Military Academy - Prominent Falkovnian military academy.
FORLORN
Forfarian Pantheon - Large resurgence of worship of the old (Celtic) gods in Forfarmax. Few actual priests.
The Morninglord - Introduced by travelling clerics from Barovia. Welcomed, though most of the druids follow the old gods.
G'HENNA
Cult of Zhakata - G'Hennan based faith centered around placating its beast god.
HAR AKIR
Green Hand - A secret cabal of Akari tomb defenders.
HAZLAN
Order of the Guardians - A monastic order of lorekeepers dedicated to finding cursed objects and keeping them out of the wrong hands.
Red Academy - Hazlik's college of witchcraft, an arcane focused school quickly rising in prominence.
Church of the Lawgiver - State religion of Hazlan and only officially sanctioned one allowed. Wide scale worship from Mulani and Rashemi alike.
Church of Hala - Operates in secret, worshiped by the Rashemi and well received by those who don't even pray to Hala.
Iron Inquisition - Lawgiver internal security and heretic hunters.
INVIDIA
Gundarkite Rebels - Organized resistance to outside rule of Gundarkite territory.
Church of Ezra - Most Invidians profess faith in one of the four sects, preference being personal taste and attitude.
Church of Hala - Secretly worshiped since being outlawed, members burnt or hung. Publically mistrusted due to its secrecy.
KARTAKASS
Brotherhood of Broken Blades - Vigilante witch-hunters dedicated to wiping out abusers of magic. Well-meaning but reportedly often vague in defining who is an "evil" magician.
Howling Clan - Wolf God heretics who embrace their savage humanity, led by Mother Fury
Ancestral Choir - Main theological belief system. Handful of priests who serve to continue the traditions and gaurd the souls of the dead joining the Choir.
Church of Ezra - Few converts, stratified social structure being a concept most Kartakans abhor.
Church of Hala - Unobtrusive hospices, seldom regarded or thought much of beyond being healers.
LAMORDIA
Van Richten Society - A loose alliance of correspondents who seek to continue Van Richten's legacy.
Syndicate of Enlightened Citizens - Lamordian conspiracy with designs against the supernatural.
MARKOVIA
Order of the Guardians - A monastic order of lorekeepers dedicated to finding cursed objects and keeping them out of the wrong hands.
MORDENT
2nd Sect of Ezra - LG "Pure Hearts" centered in the Chapel of the Pure Hearts. Large following due to its benevolent dogma though Home Faith is also present.
Lamplighters - School of policing that originated in Mordent, and has recently been exported to other domains. Known for rigorous honesty.
Van Richten Society - A loose alliance of correspondents who seek to continue Van Richten's legacy.
Order of the Guardians - A monastic order of lorekeepers dedicated to finding cursed objects and keeping them out of the wrong hands.
Church of Hala - Accepted though often regarded as playing with fire due to the nature of melding the arcane and divine, inviting the influence of the forces of darkness.
NIDALA
Knights of the Shadows - A venerable knighthood that struggles against tyranny in all of its guises. While not actually based in Nidala, it is the one place they make a pilgrimage to that's constant.
Church of Belenus - Puritanical version of the faith, actively castigates "sinners" and purges non-humans.
NOVA VAASA
Syekhmetskaya Circle - Nova Vaasan based criminal organization said to be controlled by the shadow genius Malken.
Church of the Lawgiver - Only religion in Nova Vaasa, actively imprisons "heretical" clerics of other faiths if caught.
RICHEMULOT
The Lock and Key - A Richemoluise cabal of masked Caliban watchmen, known for their strict code of honor and justice.
Van Richten Society - A loose alliance of correspondents who seek to continue Van Richten's legacy.
The Cult of Simon Audaire - A conspiracy of disaffected human Reniers plotting against their kin.
The House of a Hundred Moths - Richemuloise arcane university that maintains a vague cover as an astrological institute.
Church of Ezra - All four sects present, largely casual lipservice following among worshippers.
Church of Hala - Widespread presence among commoners, mistrusted by nobility.
SITHICUS
The Order of the Guardians - A monastic order of lorekeepers dedicated to finding cursed objects and keeping them out of the wrong hands.
SRI RAJI
University of Tvashtri - Only major school outside of the Core, known for religious and scientific study.
TEPEST
Order of the Guardians - A monastic order of lorekeepers dedicated to finding cursed objects and keeping them out of the wrong hands.
Tepestani Pantheon - Large devotion to various (Celtic) gods with Belenus as the chief one.
Tepestani Inquisition - Loose organization of priests in Tepest who have declared war against the night, also known to brutalize elven folk.
Church of Ezra - Marginal following, has often protected innocents against the Tepestani Inquisition.
Church of Hala - Largely devoted to rooting out the domain's hags and goblins. Executed by Inquisition as witches if found.
Church of the Lawgiver - Has a small presence but proven unpopular with the commoners for its superior attitudes.
VALACHAN
Cult of Yutow
Church of Ezra - Small presence in Helbenik. Faith's compassionate teachings appeals to some.
Church of Hala - Large, unobtrusive persence. Popular although careful it does not act in conflict with Yutow.
VREBREK
Cult of the Wolf God - Most common religion though no human settlements worship it. Worshipped solely by werewolves and placated out of fear. The enemy of all men.
Church of Ezra - Small presence, Home Faith the sect of choice among its worshippers.
Church of Hala - Highly regarded, witches honoured for fighting the werewolves. Unpopular with th elycans who actively hunt its clerics. Operates well hidden sacred groves.
Woodcutter's Axe - Organised human rebels fighting the oppression of the werewolves.