Thalek (Auld Mortality's universe)

The Thaleks were a race that conquered half of Mutter's Spiral. Their war cry was "Annihilate!".

The Doctor was worried about their actions and the fact that Time Lords did nothing to stop them; he later encountered them during his travels, after he left Gallifrey. (AUDIO: Auld Mortality)

Behind the scenes
The Thaleks were created as an unbound counterpart for the Daleks. Both races were warrior races, had a similar battle cry and are seen as a threat for the universe by the Doctor.