Almost all NPCs and creatures in Skyrim belong to one or more factions (or guilds). These faction memberships control the combat reaction of all NPCs and creatures, both towards the player and towards one another. Your character can be a member of more than one faction at a time.
 Joinable Factions
There are four primary factions that the player can join.
- Companions — A guild of mercenaries, dedicated to combat, based in Whiterun. They are similar to the Fighters Guild in previous games.
- The Circle — The most trusted and accomplished members of the Companions.
- College of Winterhold — A guild dedicated to the study and practice of magic and based in Winterhold. They are similar to the Mages Guild of previous games.
- Thieves Guild — A secret guild dedicated to professional thievery, based in Riften.
- Dark Brotherhood — A secret guild made up of professional assassins, the same as from previous games.
The player may also take part in the civil war by joining one of these two factions.
- Imperial Legion — The military power of the empire, they seek to maintain Imperial control of Skyrim from their base in Solitude.
- Stormcloaks — The main organization of rebels in Skyrim's civil war, they seek Skyrim's independence from the Empire. They are based in Windhelm.
This joinable faction doesn't have its own lengthy quest chain.
- Bards College — A guild of musicians, vocalists, and story tellers, based in Solitude. They have a single quest to join and a few sidequests for members.
Two new factions become available with the Dawnguard plug-in.
- Dawnguard — An order of vampire hunters.
- Volkihar Vampire Clan — A clan of vampires trying to blot out the sun.
 Noteworthy NPC Factions
- Blackblood Marauders — A group of bandits based out of Broken Oar Grotto.
- Blades — An order of warriors that once served the Emperor before being disbanded and nearly exterminated by the Thalmor.
- Blood Horkers — A group of pirates based out of Japhet's Folly.
- Forsworn — Primitive Bretons native to The Reach who want to overthrow the region's Nord rulers.
- Greybeards — A monastic order dedicated to studying and preserving the Way of the Voice.
- Penitus Oculatus — An Imperial espionage organization responsible for protecting the Emperor; it rose to prominence after the disbandment of the Blades.
- Psijic Order — An ancient and mysterious monastic order that practices arcane magic and opposes the Thalmor.
- Silver Hand — Werewolf hunters that oppose the Companions.
- Summerset Shadows — A group of thieves based in Windhelm that steal valuables from the corpses of the dead.
- Synod — One of two competing mage organizations in Cyrodiil which formed when the Mages Guild splintered.
- Thalmor — The ruling faction of the Aldmeri Dominion, it seeks to establish elven supremacy over the race of men.
- Vigil of Stendarr — A militant holy order of Stendarr adherents founded after the Oblivion Crisis, its members are dedicated to hunting Daedra.
 Group Combat Reaction
 Complete Factions List
A full list of all non-Dragonborn factions (including those not available to the player), along with their members and interrelationships, can be found at the pages below: