Qetesh

The Qetesh were a species that fed off excitement in people's lives, draining their life essence with it. They were masters of emotional manipulation, and were also known as "soul-stealers". (SJA: Goodbye, Sarah Jane Smith)

Biology
The Qetesh outwardly resembled humans, though they possessed far greater strength. Their stomachs existed outside their bodies and they did not need air to breathe. (SJA: Goodbye, Sarah Jane Smith)

History
The Qetesh imprisoned one of their species, who took on the name Ruby White. They placed the prison craft into space; however, Ruby managed to escape. She then travelled to many planets and drained them. Ruby was eventually recaptured by Sarah Jane Smith. (SJA: Goodbye, Sarah Jane Smith)