Thalek (Auld Mortality)

The Taleks 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. (NOTVALID: 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 treath for the universe by the Doctor.