On her web site, JKRowlings says that Crookshanks isn't n animagus but isn't a pure cat either. Crookers is half Kneazle.
She goes on to say that you can find out what a Kneazle is in a book called Fantastic Beasts and Where to Find Them. The books been sold to raise money for famine relief so it sounds like the thing to own but I don't.
Does anyone out there have the book?
Does anyone know what a Kneazle is?
Do they have any powers? - Crookshanks is remarkable smart.
Sounds strangely familiar. Have we been introduced to them in Care of Magical Animals?