The Ageless were a race who met with the Tenth Doctor to discuss the fate of Species 29 and Species 7.
Biology
The Ageless were immortal. This was because, according to the Doctor, 'it takes them an eternity to get anything done'. (PROSE: Cats and Dogs)
Culture
The Ageless had invented a new colour, called frume. (PROSE: Cats and Dogs)
Technology
They had Transdimensional Matter Restorative, which gave them the ability to remove a person's mind from their body. This forced them into an incorporeal state. They also had large, conch-shell shaped spaceships. (PROSE: Cats and Dogs)
History
The Ageless were involved in the war between Species 29 and Species 7. They ended the war by trapping both species in an incorporeal state. A thousand years later, they held a trial for both species, to decide if they could be allowed their bodies back. Thanks to the Doctor they decided not to give the Species 29s and Species 7s their bodies back. (PROSE: Cats and Dogs)