Cheshire cat

When Biroc left while having a conversation with the Fourth Doctor, the Doctor said it was like talking to a Cheshire cat. (TV: Warriors' Gate) Bernice Summerfield, while losing consciousness, saw Carrefour's teeth slowly vanish "like those of a demonic Cheshire cat." (PROSE: White Darkness)

There existed an individual known as "the" Cheshire Cat, whom Iris Wildthyme encountered. (PROSE: Iris Wildthyme and the Polythene Terror) While visiting Wonderland, Iris and Panda had previously confused the Salford Cat for a Cheshire cat, only to be told that a Salford cat was "something else entirely". (AUDIO: Iris Wildthyme and the Land of Wonder) The Cat, a virtual being created by the Doctor's TARDIS to help the Eighth Doctor recover from the influence of Zagreus, was patterned after the Cheshire Cat as depicted in Alice in Wonderland. (AUDIO: Zagreus)