What is the name of the mystery cat in T. S. Eliot's book "Old Possum's Book of Practical Cats"?

Macavity is a fictional character who is described in a poem in "Old Possum's Book of Practical Cats", by T. S. Eliot. He also appears in "Cats", the Andrew Lloyd Webber musical.

The poem "Macavity the Mystery Cat" is the best known of Eliot's "Old Possum's Book of Practical Cats", the only book Eliot wrote for a younger audience. The poem is considered particularly suitable reading for 11- and 12-year-olds.

The name Macavity is a pun by T. S. Eliot, on the names of several characters from other works of literature : Macheath, a supervillain who appears both in John Gay's "The Beggar's Opera", its sequel "Polly" and roughly 200 years later as Mack the Knife in "The Threepenny Opera" written by Bertolt Brecht and Kurt Weill in 1928, macuahuitl, the Aztec obsidian sword, and Moriarty, the surname of a supervillain-scientist from the Sherlock Holmes stories by Arthur Conan Doyle. Lastly, the word 'cavity' implies a hole or void or absence of something, and he is described in the poem as being "not there" at the time or location of any crime.