Many years ago, the Daleks sent out thousands of egg-shaped Progenitors containing the genetic coding of the race, so that new Daleks could be created whenever necessary. One of these Progenitors was found in war-torn England during the Second World War and transported to a Dalek ship. However, because the Daleks that found it had been genetically modified by their creator Davros, using his own DNA, the Progenitor did not acknowledge them as pure Daleks, until the Doctor identified them as such and the Progenitor created a new race of powerful Daleks as a result.

These Daleks were led by the white-cased Supreme, and include the enigmatically titled yellow-cased Eternal, blue-cased Strategists, orange-cased Scientists and the red-cased Drones.