- You may be looking for the predatory, non-sentient cats.
The Tigers were a species of shapeshifters. They could take the form of a human or a tiger.
The tigers were nearly wiped out, but two were able to escape to Earth, later to be known as Lady Huntingdon and Bella Huntingdon. Lady Huntingdon planned to find a way back in time and tried to steal Iris Wildthyme's TARDIS. The Fourth Doctor was able to seal her inside a message pod. Her granddaughter stayed on Earth and married Edwin Turner, Iris' abandoned companion. (PROSE: Old Flames)