Ruby White

Ruby Anne White was the cover identity of a Qetesh who came to Earth intending to feed off of Sarah Jane Smith. She owned an artificial intelligence that was named Mr White by Clyde Langer.

"Ruby" was imprisoned by her own race on a prison ship, with only a games console for entertainment, due to her uncontrollable hunger for the fear, excitement and life force of other beings. Over a long time she reprogrammed the games console into an AI to serve her needs, turning the prison into a working spacecraft. She went to many planets, draining and feeding off the inhabitants.

When she came to Earth, she posed as a human named Ruby White. She researched Sarah Jane Smith, who led the most exciting life on Earth. She moved into a house on Old Forest Road, near Bannerman Road, hiding her stomach — a physically separate part of her being — in a cellar. She used her AI to simulate a meteor and a formidable alien race on separate occasions so that the Bannerman Road gang would try to stop them, but find Ruby there to save the day ahead of them. She gained the trust and friendship of Sarah Jane, Clyde, and Rani, but secretly drained Sarah Jane's life force and made her ill and confused. After having her suspicions of her own mental deterioration confirmed by Mr Smith's medi-scan, Sarah Jane mistook her symptoms for getting too old and infirm to continue defending Earth. Sarah Jane gave Ruby everything, including 13 Bannerman Road and control of Mr Smith. She implored her to keep on her activities in defence of Earth with the Bannerman Road gang. After the transfer, Ruby revealed her true intentions and transported the weakened Sarah Jane in Ruby's own "secret cellar" with her stomach, continuing to slowly drain her fear.

She teleported Clyde Langer to her prison ship but was tricked by Rani Chandra who, with Luke Smith and K9 Mark IV, gained control of Mr White, teleporting Clyde back and restoring Mr Smith to normal. The teenagers ran to find Sarah Jane and Ruby followed them.

Luke defeated her by using Mr White to simulate meteors falling to Earth on a massive scale, causing all six billion people on the planet to simultaneously experience enough fear and excitement to overload Ruby's stomach. Ruby was returned to her prison by a restored Sarah Jane, but vowed revenge on her and the entire Earth as her once-again uncontrollable prison flew away.

_{Biography from the TARDIS Data Core article, licensed under CC-BY-SA}