Mitzi
Mitzi was an Earth cat that had been sent into hyperspace by human scientists. While stranded in space, she gained intelligence and a extended lifespan from an unknown energy. With this intelligence, she was moved to terraform the world she landed on.
When humans came to inhabit it, Mitzi took control over them and forced them to serve her. Ninety years after her arrival, the Tenth Doctor and Rose Tyler landed on the planet. She planned to return to Earth and spread her gift to the rest of animal kind.
The Doctor confronted her, pointing out the flaws in her argument, to which she attempted to execute him. Just at that moment, her link to the energy was broken by Rose, and Mitzi returned to being an ordinary cat. Mitzi took a trip in the TARDIS and was taken to the Powell Estate. Rose told the Doctor that she had found Mitzi and renamed her Puffin in her past. She lived for another five years under the Tyler family's care. (PROSE: The Cat Came Back)
When the the Ninth Doctor was investigating the Autons, Rose Tyler told him the reason she had a cat flap was that she used to have a cat. (TV: Rose) Rose later remarked she had a cat like the ginger one she befriended in 2012. (TV: Fear Her)
