Brilliant Quidditch Changing Room
Gryffindor Common Room, Hogwarts Castle
Crookshanks was Hermione Granger's pet during her time at Hogwarts. Part cat, part Kneazle, and by all accounts grumpy, he was said to have been uncharacteristically intelligent and cognizant. This is perhaps best evidenced in the role he played in revealing Ron Weasley's pet rat, Scabbers, as Peter Pettigrew in his Animagus form.