Old One

The Old Ones is the term used to refer to the extremely powerful pure-breed demons that once dominated earth before humankind appeared. Illyria is one of these demons, though her real form was revealed only in an illustration.

Background
The information regarding the Old Ones is limited. Giles tells Buffy in "The Harvest":


 * "This world is older than any of you know. Contrary to popular mythology, it did not begin as a paradise. For untold eons demons walked the Earth. They made it their home, their...their Hell. But in time they lost their purchase on this reality. The way was made for mortal animals, for, for man. All that remains of the Old Ones are vestiges, certain magicks, certain creatures..."

What is known about the Old Ones is that they were not the first beings to inhabit this dimension. The Old Ones were preceeded by the beings that would be eventually known as The Powers That Be. The rise of the Old Ones led the Powers to leave this world, while the Old Ones became rulers of vast territories, commanded enormous armies that worshipped them as gods and constantly made war against each other.

In time mortal animals arose, and then mankind appeared. Modern demon races, such as vampires, appeared due to various types of hybridization between the Old Ones and men or other species.

It is unknown how is it that the Old Ones lost their rule over earth. In any event, they were either killed in their own wars (such as Illyria) or driven away to other dimensions. Those who were killed were placed in sarcophagus which were hidden at the Deeper Well, a true hole in the world running between the Costwolds and Australia, where the remains of the Old Ones were supposed to be kept in order to prevent their resurrection, as not only their corpses, but also their essences were trapped.

The legacy of the Old Ones remained not only in the form of the hundreds of demon species that exist today, but also in the form of cults which worship them and await their return to usher the destruction of mankind.

Even though they are unable to manifest in this dimension on their own, the Old Ones would be able to return if a portal to the hell dimensions they dwell is opened. Also, they are capable of infecting reality and causing severe deformities, mutations and insanity if summoned via artifacts such as the Key of Amon-Rathna, which affected Council members Thorton Whitney, Alan, Barbara and Graham Locke, the latter becoming a doorway for the Old Ones to return.

Biology and Powers
Each Old One has a different shape and powers. What they all share though is their enormous size.

Known Old Ones

 * The Hellmouth Spawn
 * Olvikan
 * Lohesh
 * Ky-laag
 * Illyria