Crookshanks was the name of Hermione Granger’s pet cat. She found him at the beginning of her third year when the trio had gone to the Magical Menagerie pet shop.

The Definitive Glossary for Harry Potter

Crookshanks was half-kneazle and was, therefore, more intelligent than house cats. He was responsible for the successful apprehension of Peter Pettigrew, who disguised himself in his Animagus form of a mouse as Ron Weasley’s pet rat Scabbers. Hermione loved Crookshanks a lot and would stand up for him despite Ron’s constant remarks about Crookshanks trying to attack Scabbers.

Crookshanks first appeared in Harry Potter and the Prisoner of Azkaban when Ron, Harry and Hermione went to the Magical Menagerie pet shop to buy something that would cure Ron’s pet rat Scabbers. Crookshanks suddenly jumped from a shelf towards them and Hermione took an instant liking to him.


It is possible that Crookshanks was named after the famous wizard Poderick Crookshank. It is also possible that Crookshanks was named after a surname from Scotland called “Cruikshank” as George Cruikshank, the famous illustrator from the 19th century, illustrated Oliver Twist, which was the work of one of J. K. Rowling’s literary influences, Charles Dickens.


Crookshanks appeared like most other bushy house cats but had a lion-like appearance and a bottle-brush tail to go with it. It is believed that Crookshanks’s appearance was inspired by a cat that J. K. Rowling came across when she worked in London. This cat would prowl around some sunbathers in the place she would eat her lunch on sunny days. Rowling believed that this cat must be from a nearby house, and despite her hesitation to go close to the cat and risk getting an asthma attack, she liked this cat and based the appearance and demeanor of Crookshanks on this cat. Crookshanks was a smart cat and made a great pet for a bright witch like Hermione.

Early Life

Very little is known of Crookshanks except that he was part-kneazle and stayed in the Magical Menagerie, Diagon Alley, in London, before Hermione bought him as her pet on 31 August 1993. It is possible that Crookshanks was born in the late 1980s. Although she was initially planning to get a new owl as a pet, she developed an interest in Crookshanks and got him as her pet instead. The owner of the shop had mentioned that he had been there quite some time and that nobody wanted him, which must have influenced Hermione into getting him as her pet.

At Hogwarts

Hermione decided to take Crookshanks with her to Hogwarts in her third year. Crookshanks was present in the compartment when the Dementors made an entrance in search of Sirius Black. Early into their third year, Crookshanks started trying to attack Scabbers, Ron’s pet rat. Initially, there is a scuffle between the two when Ron mentions that Scabbers was in his bag, and this caused an argument to break out between Ron and Hermione. Eventually, Crookshanks would constantly attack Scabbers at every possible opportunity causing Ron to ask Hermione to keep him out of sight whenever Scabbers was in the room.

Ron found some blood on his bedsheet in his room in the Gryffindor Tower and was convinced that it was Crookshanks who had eaten Scabbers. However, Scabbers was found later in Hagrid’s hut, and Ron heaved a sigh of relief. 

Crookshanks was at the center of the events that unfurled on 6 June 1994 and helped Sirius lure Harry, Ron, and Hermione out of the castle. Since Crookshanks was half-kneazle, he had a knack for identifying untrustworthy persons and that is why he had tried to attack Scabbers several times. Before 6 June, Crookshanks had also helped Sirius enter the Gryffindor Tower by giving him the piece of paper that Neville Longbottom had misplaced. This paper contained the passwords needed to enter Gryffindor Tower. Sirius later claimed that Crookshanks was a remarkable animal companion.

On 6 June 1994, Scabbers tried to run away when Crookshanks tried to chase him, but Ron somehow managed to catch hold of him. That is when Sirius emerged in his Animagus form as Padfoot, a dog. He caught hold of Ron’s leg and dragged him into the Shrieking Shack through the Whomping Willow. When Harry and Hermione tried to enter, the Whomping Willow attacked them. However, Crookshanks helped them by touching the right knot on the bottom, and they were granted access.

Eventually, it was revealed that Crookshanks had been attacking Scabbers not because he was a rat but because Scabbers was Peter Pettigrew in Animagus form. Peter had betrayed James and Lily Potter by revealing their location to Lord Voldemort and, when confronted by Sirius, pretended to die and killed several Muggles in the process and escaped. Sirius was accused of the murder of Peter Pettigrew, and ever since then, Peter had been hiding as Wormtail and had eventually decided to stay at the Weasley household. Crookshanks plays a major role in saving Sirius from Harry by hoisting himself on Sirius’ heart when Harry points his wand to kill him. Remus Lupin and Severus Snape eventually came to the Shrieking Shack, and the truth was revealed.

However, as they caught Peter Pettigrew and decided to return to Hogwarts with him, Lupin turned into a werewolf as he had forgotten to take the Wolfsbane potion that day. Pettigrew escaped again after stunning Ron and Crookshanks with his wand and was not caught.

Later Life

Crookshanks continued to spend time with Hermione and her friends, and Ginny Weasley, who was fond of cats, also liked Crookshanks a lot. Ron eventually forgave Crookshanks for attacking Scabbers after it was revealed that he was Peter Pettigrew. He even held his new pet owl Pigwidgeon toward Crookshanks for him to approve as Ron’s new pet. Crookshanks would sometimes sit on Harry’s lap as he was fond of Harry.

Crookshanks stayed at Twelve Grimmauld Place for a while when Hermione was visiting and interfered with the Extendable Ears that the Weasley Twins were using to listen into the Order of the Phoenix meetings. During the events of Harry Potter and the Deathly Hallows, Crookshanks stayed in the burrow when Hermione went in search of Voldemort’s Horcruxes with Ron and Harry.

The Fan Theory About Crookshanks

One of the most popular fan theories about Crookshanks is that he used to be Lily and James Potter’s cat. There is a brief mention of a cat in the letters that Lily wrote to Sirius thanking him for the toy broomstick he gifted Harry for his birthday and that Harry almost knocked the cat over while playing on his broomstick. However, we believe that it is highly unlikely that Crookshanks is the cat that Lily is referring to because it is very likely that Sirius would have mentioned that Crookshanks looked similar or was the cat that belonged to Harry’s parents.

There is still a possibility that Crookshanks was Lily’s cat after all and that he may not have recognized Harry as he had grown, and that Crookshanks took time to trust Sirius because it had been a long time. It is also possible that Sirius never met this cat at the Potters’ if they happened to adopt it after they went into hiding.


Is Crookshanks an Animagus?

No, Crookshanks was not an Animagus. He was a cat. However, he was a half-kneazle and a half-cat. Therefore, he was different from other house cats with respect to several properties. He was highly intelligent and could tell if there were untrustworthy people in his midst.

Was Crookshanks helping Sirius?

Yes, Crookshanks was helping Sirius Black. Crookshanks was a highly intelligent cat, and he knew that Scabbers was an Animagus in disguise and couldn’t be trusted. Therefore, he decided to help Sirius catch Scabbers after he realized that Sirius was trustworthy.

Was Crookshanks Lily Potter’s cat?

It is highly unlikely that Crookshanks was Lily Potter’s pet cat before he was adopted by Hermione. This is because Sirius Black, who was very close to the Potters didn’t make any mention of Crookshanks resembling that cat. Furthermore, Sirius claimed that Crookshanks took a while before he trusted Sirius, which probably wouldn’t be the case if Crookshanks knew Sirius already. However, the possibility still exists that Crookshanks was Lily Potter’s cat after all. However, there is no way to tell.

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