Eternal

Not possessing the power of creativity themselves, the Eternals utilise the thoughts and emotions of so-called Ephemerals for their own ends.

Characteristics
The Eternals dwell in the domain of Eternity rather than the small one of Time. Unaffected by Time and thus unaging, as their name would suggest, the amoral Eternals make it their principal aim in life to amuse themselves, using Ephmerals as their toys. These games were started by the Guardians of Time, whom the Eternals greatly respect as leaders. (PDA: The Quantum Archangel) Though they are related to the Chronovores, they looked down on them as vicious predators. (PDA: The Quantum Archangel)

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

Powers
Eternals could use telepathy and create objects from the memories or Ephemerals. They could also make objects vanish. (DW: Enlightenment)

History
The Eternals are, as their name suggests, eternal, therefore a history of their race would be hard to find. However, the first event that they are known as doing was the banishment of the Carrionite race into the Deep Darkness. (DW: The Shakespeare Code)

Until he met the Doctor and probed his mind, the Eternal known as Striker said that he had never heard of the Time Lords. (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), however, carnage of the Time War horrified even the aloof Eternals to the extent that they left this reality. (DWA: Doctor Who Annual 2006)

Sebestiene claimed to have hunted down an Eternal. (TDA:The Doctor Trap)