Clever Crookshanks belongs to none other than Hermione Granger, Brightest Witch of Her Age™ from the Harry Potter series. He’s half-Kneazle, half-cat, and fully adorable. (Harry would say that’s a matter of opinion, but I would say he’s wrong.)
He’s described as having a thick, fluffy ginger coat, a bottlebrush tail, a squashed, grumpy face, and slightly bandy legs. Per the Harry Potter Lexicon, his name is taken from the surname Cruikshank, which means “crooked legs.”
He bursts into the Potterverse for the first time in Harry Potter and the Prisoner of Azkaban at the Magical Menagerie pet store in Diagon Alley when he yeets himself at Ron and nearly kills him.
Hermione sees this and thinks, “I need this creature in my life.”
“Okay,” said Ron. “How much—OUCH!”
Ron buckled as something huge and orange came soaring from the top of the highest cage, landed on his head, and then propelled itself, spitting madly, at Scabbers.
“NO, CROOKSHANKS, NO!” cried the witch, but Scabbers shot from between her hands like a bar of soap.
It took them nearly ten minutes to catch Scabbers, who had taken refuge under a wastepaper bin outside. Ron stuffed the trembling rat back into his pocket and straightened up, massaging his head.
“What was that?”
“It was either a very big cat or quite a small tiger,” said Harry.
“Probably getting her owl.”
Hermione came out, but she wasn’t carrying an owl. Her arms were clamped tightly around the enormous ginger cat.
“You bought that monster?” said Ron, his mouth hanging open.
“He’s gorgeous, isn’t he?” said Hermione, glowing.—Harry Potter and the Prisoner of Azkaban
As Potterheads know—and as his fictional humans did not at the time—Crookshanks was only trying to attack a Death Eater in disguise, like a good boy. Hermione obviously made a smart choice in her familiar, but Crookshanks was smart to choose Hermione too. Throughout all his prowlings of the Hogwarts grounds after Hermione took him to school with her—when he could’ve dipped out forevs—he always wound up back home in front of the fire in Gryffindor Tower.
I’m of the mind that cats are like wands: they choose the wizard.
Other things Crookshanks was smart about in Prisoner of Azkaban include knowing that Sirus Black was always to be trusted and how to calm the Whomping Willow by touching a knot in the trunk.
“He’s the most intelligent of his kind I’ve ever met.”—Sirius Black
Not only that, he managed to single-pawedly orchestrate Sirius’ break-in of Gryffindor Tower by stealing the portrait passwords from Neville’s bedside table. I’ll say it again. A CAT. Helped the most WANTED criminal in Britain break into Hogwarts. Good job, school.
J. K. Rowling’s decision to give Hermione an unusually intelligent cat was inspired by a real-life, large, fluffy ginger cat that hung around the square where she ate lunch when she worked in London. The cat, who “looked as though it had run face-first into a wall,” prowled around with a disdainful look, avoiding peoples’ attempts to stroke it. Rowling never got close but became “distantly fond” of the cat.
In the Harry Potter series, Rowling made Crookshanks a bit friendlier than his IRL counterpart—he purrs loudly and curls up in laps often, Harry’s included. Even Ron, who seems to be yelling at or about Crookshanks on every other page in Azkaban, comes around to sort of liking him, offering his new pet owl Pigwidgeon to him at the end of the book for the Crookshanks Seal of Approval Sniff Test™.
This bushy-haired boy may have been a little misunderstood throughout his page-time in the books because of his intelligence, but as I’m sure his bushy-haired mom would agree, intelligence is a trait worth being misunderstood for.
The common room was almost empty; nearly everyone was still down at dinner. Crookshanks uncoiled himself from an armchair and trotted to meet them, purring loudly, and when Harry, Ron and Hermione took their three favorite chairs at the fireside he leapt lightly on to Hermione’s lap and curled up there like a furry ginger cushion.—J.K. Rowling, Harry Potter and the Order of the Phoenix