Oblivion

Oblivion is a different plane of existence inhabited by Daedric princes or lords, each of whom has their own realm or realms within. There are also other realms which are not directly ruled by daedric princes.

General
By the Alessian Doctrines of the first era prophet Marukh, who neglected to explain what are the daimons in his words, we customary refer to the citizens of the dimension of Oblivion as "demons". The old Elven word, Daedroth (Daedra in plural) refer to a strange and powerfull creatures who hail from the dimension of oblivion. The first names coming from that dimension were introduced in words a thousand years before the first Doctrine, by King Hale the Dious of Skyrim, refering to his political enemies:

'the wickedness of the demons of Oblivion... Their depravity equals that of Sanguine itself, they are cruel as Boethiah, calculating as Molag Bal, and mad as Sheogorath.'

With this words, Hale the Dious thus long windedly introduced four of the Daedra lords to written records. Oblivion is composed by many lands, each land is ruled over by one prince. Its hard to define and categorize the Daedra, they're a very mixed lot. Daedra are dangerous of course. More information about Oblivion soon.

Source: Skyrim, "On Oblivion" by Morian Zenas

Realms within Oblivion

 * Apocrypha
 * The Ashpit
 * Attribution's Share
 * Chimera of Desolation
 * Clavicus Vile's realm
 * Coldharbour
 * Deadlands
 * Evergloam
 * Gaiar Alata
 * Havoc Wellhead
 * Hircine's Hunting Grounds
 * Mephala's Web
 * Meridia's Colored Rooms
 * Moonshadow
 * Peryite's Pits
 * Sanguine's realms, of which there are a reported one hundred thousand
 * Scuttling Void
 * The Shivering Isles
 * Soul Cairn
 * Vaermina's Quagmire