Umbra

Umbra is a dangerous, shadowy realm described as a graveyard for worlds. Worlds that are scourged of life and are unanchored disappear into the primordial abyss of Umbra.

There are many large and monstrous beings (referred to as "abyssal creatures") that originate in Umbra. The armies of the Endless Kingdom and others sometimes employ such creatures in their forces.

During the Dawnguard raid it was revealed that War's Soul resided in Umbra during the century that he was imprisoned and that the Aberrant originated from this realm.

The Abberant
The Abberant are five creatures from the Abyss more ancient than demons who are the Destroyer's most trusted and powerful underlings. The Abberant are :
 * Tiamat - A huge bat-like creature that dwells in the Twilight Cathedral.
 * The Griever - A giant insect who has made The Hollows her lair.
 * The Stygian - The largest and strongest Ashworm within The Ashlands
 * Silitha - A monstrous spider creature similiar to Achidna who dwells in Silitha's Loom within the Iron Canopy.
 * Straga - The general of the demonic invasion of Earth, he is one of the Chosen, but his heart is the only one Samael doesn't need. His spire originates from the Black Throne, and he is loyal to the Destroyer.