Eternal

The Eternals were beings of immense power, but limited creativity, who utilised the thoughts and emotions of so-called Ephemerals for their own ends.

Characteristics
The amoral Eternals made it their principal aim in life to amuse themselves, using Ephemerals as their toys. (DW: Enlightenment) In the course of their games, the Eternals would sometimes pose as gods and doom whole worlds in the process. (DWM: Uninvited Guest) These games were started by the Guardians of Time, whom the Eternals greatly respect as leaders. (PDA: The Quantum Archangel)

Though they were related to the Chronovores, they looked down on them as vicious predators. The Ancient Compact prohibited a union between the two beings. However, the great Kronos arose from one of such union. (PDA: The Quantum Archangel)

Through somewhat obscure means, as a punishment, the Doctor used the force of the Time Vortex itself to bring the particularly callous Lord Prospero and his social circle into the domain of Time, which would indicate that under circumstances they can transition from Eternal to Ephemeral. (DWM: Uninvited Guest)

Powers
The Eternals dwelt in the domain of Eternity rather than the smaller one of Time, which meant they were unaffected by Time and thus unaging. Eternals could not be destroyed, only transferred. Eternals could also use telepathy and create objects from the memories of Ephemerals. Their powers were not limitless and they could not read minds from great distance or from strong minds. (DW: Enlightenment) They could also appear in dreams. (NA: Love and War)

History
The Eternals were, as their name suggests, eternal, therefore a history of their race would be hard to find. However, the first event that they are known to have done was to banish the Carrionites into the Deep Darkness during the Dark Times of the Universe. (DW: The Shakespeare Code)

Some of the Eternals passed themselves off as the Gallifreyan's deities such as Time, Pain and Death, a development which Lady President Romana found distressing. (NA: Happy Endings) Not all Eternals did this, and until he met the Doctor and probed his mind, the Eternal known as Striker professed that he had never heard of the Time Lords. (DW: Enlightenment)

At some point, the Guardians of Time set up a race for a group of Eternals, with Enlightenment being the prize. Groups of Eternals copied ships from various points in Earth's history, fitted them with ion drives and sails to catch solar winds and kidnapped Humans to run the ships. Though Captain Wrack almost won the race by destroying the ships of her enemies, the Doctor managed to push her off her ship and bring it to the Guardians of Time. (DW: Enlightenment)

The carnage of the Last Great Time War horrified even the aloof Eternals to the extent that they left this reality. (DWA: Doctor Who Annual 2006)

The Doctor later refers to the Eternals as though they did not leave the universe as he warns the Hervoken to beware of attracting the Eternals attention. (NSA: Forever Autumn)

Other information

 * The Eternals referred to the Void as "the Howling". (DW: Army of Ghosts)
 * Sebestiene claimed to have hunted down an Eternal. (NSA: The Doctor Trap)
 * Adam, an alien who infiltrated Torchwood 3 showed similar powers to an Eternal, he also said that he had escaped from the Void. (TW: Adam)