Chaon

Chaon were, according to Genetic Variant Two-One-Zero, a natural predator of the Daleks that came from deep space, with a genetic code in continuous flux. They could absorb energy from the environment to change their physiology at will, and were able to rebuild themselves, growing a new limb or organ is seconds. They could suck the life-force from anything, with an insatiable appetite. The Dalek Prime and Steven Taylor encountered them on the planet Shade. (AUDIO: Across the Darkened City)