Panther

s were a type of felid mammal the Third Doctor and the Brigadier once encountered at a zoo, early in the Third Doctor's life. Normally fierce, this was as docile as an ordinary house cat. This odd behaviour made the Doctor and UNIT suspicious of nearby activities. (TVC: The Arkwood Experiments)

The Second Doctor, John and Gillian also encountered a panther. Once, while visiting New York City, the trio went to a zoo and ran into a panther that was being controlled by a misguided human scientist. The Doctor was only able to avert the panther's unnaturally aggressive attack by using acid against it. (TVC: The Monsters from the Past)

On Christmas Eve 1941, the Eleventh Doctor claimed there were panthers on an upstairs floor of Uncle Digby's house. (DW: The Doctor, the Widow and the Wardrobe)