A Black Dalek known as a Supreme Controller directed the Bedfordshire operation nearing the end of the 22nd century occupation of Earth. It had a terrifying pet called the Slyther which it used to let roam free around the mines at night, killing those it found. The Supreme Controller was killed when the Dalek bomb detonated as Ian Chesterton had sabotaged the bomb. The Supreme Controller's voice was considerably higher than those of the other Daleks. (TV: The Dalek Invasion of Earth)