Já foi revelado o que Crookshanks é?

Sim; Crookshanks é meio-Kneazle.

De site do JK Rowling :

Crookshanks, as anybody who has read Fantastic Beasts and Where to Find Them will have guessed, is half Kneazle. And if you don't know what a Kneazle is, you need to hurry up and buy Fantastic Beasts and Where to Find Them (all royalties go to help some of the poorest children in the world).

Você também pode querer verificar a página Crookshanks no Wiki de Harry Potter .

Crookshanks é meio Kneazle.

J.K. Rowling sugeriu isso pela primeira vez em sua descrição de um Kneazle em Animais Fantásticos e Onde Habitam e em um comentário em seu antigo site.

Kneazle
M.O.M. Classification: XXX

The Kneazle was originally bred in Britain, though it is now exported worldwide. A small catlike creature with flecked, speckled, or spotted fur, outsize ears, and a tail like a lion’s, the Kneazle is intelligent, independent, and occasionally aggressive, though if it takes a liking to a witch or wizard, it makes an excellent pet. The Kneazle has an uncanny ability to detect unsavoury or suspicious characters and can be relied upon to guide its owner safely home if they are lost. Kneazles have up to eight kittens in a litter and can interbreed with cats. Licences are required for ownership as (like Crups and Fwoopers) Kneazles are sufficiently unusual in appearance to attract Muggle interest.
_{(Fantastic Beasts and Where to Find Them)}

Neither of these characters can perform magic (Filch’s Kwikspell course never worked), but they still function within the wizarding world because they have access to certain magical objects and creatures that can help them (Arabella Figg does a roaring trade in cross-bred cats and Kneazles, and if you don‘t know what a Kneazle is yet, shame on you).
_{(JK Rowling's old website - Extra Stuff - Miscellaneous - Squibs)}

Ela também afirmou isso mais diretamente em seu site e depois no twitter.

Crookshanks, as anybody who has read Fantastic Beasts and Where to Find Them will have guessed, is half Kneazle. And if you don't know what a Kneazle is, you need to hurry up and buy Fantastic Beasts and Where to Find Them (all royalties go to help some of the poorest children in the world).
_{(JK Rowling's old website - Extra Stuff - Characters - Squibs)}

Spooky Magdalen: who would win in a fight, Mrs. Norris or Crookshanks?
J.K. Rowling: It would be brutal and very close, but Crookshanks' Kneazle ancestry would bring him out on top.

E não que o Pottermore atual tenha mais autenticidade do que o wiki, mas eles confirmam isso em seu arquivo de fatos sobre Crookshanks.

Hermione’s sharp-witted pet cat, who is half-Kneazle