- "An' as fer that cat, Mrs Norris, I'd like ter introduce her to Fang some time."
- —Hagrid's intense dislike of Mrs Norris[src]
Harry Potter, Ron Weasley, and Hermione Granger often narrowly escaped the cat on their nightly trips through the school. Harry had a suspicion that she was able to see him even when he was under his Invisibility Cloak, although she may just sense someone there but cannot see. It is never told, though, whether cats, or just Mrs Norris, can see/sense Harry when he's under his cloak. Harry once got caught by her one day for tracking mud on the floor. Luckily, she shows up on the Marauder's Map.
Mrs Norris was the first victim of the Serpent of Slytherin when the Chamber of Secrets was re-opened in 1992. On Hallowe'en night, she was petrified by the basilisk when she saw its reflection in a puddle of water in front of the unused bathroom, in the second floor. Ginny Weasley, possessed by Tom Marvolo Riddle hung her from a torch bracket by her tail, where she was found by Harry Potter, Ron Weasley, and Hermione Granger. Headmaster Albus Dumbledore examined the cat but was unable to revive her. Argus Filch was devastated. Mrs Norris was revived by Professor Pomona Sprout with the help of a Mandrake Restorative Draught at the end of the 1992–1993 school year.
During the Battle of Hogwarts, Mrs Norris was seen hissing, screeching and batting at some owls who had escaped from the Owlery to return them to their proper place. It is unknown if she joined the fight with or without Filch.
Filch and Mrs Norris had an unusually close bond. Filch was extremely fond and protective of her. Even when patrolling separate corridors, the two seem to be able to communicate and Filch came directly to her when she spotted a student misbehaving. When she was attacked by the basilisk in 1992, Filch's first thought was that she was dead, and he was understandably devastated. It is unknown what happened to Mrs Norris after the war.
Rubeus Hagrid could not stand her; he suspected that Filch set her up to follow him around whenever he came up to the school. Hagrid once remarked that he would like to introduce her to Fang. However, the cat seemed to respect the other Hogwarts teachers.
Mrs Norris was hated by a majority of the students. Much like her master, she had an excellent knowledge of the castle. Being caught misbehaving by her was just as bad as being caught by Filch, because she would fetch him straight away. It was the "dearest ambition of many to give Mrs Norris a good kick."
Behind the scenes
- Mrs Norris seems exceptionally smart for a cat, to the point that many have suspected she is a cat/Kneazle cross like Crookshanks or an Animagus. However, J. K. Rowling has stated on her website that she is just a highly unpleasant cat. This was confirmed again when Rowling stated on Twitter in response to a fan query that Mrs Norris would lose in a very brutal, close fight with Crookshanks, as Crookshanks's kneazle ancestry would eventually give him the edge.
- Mrs Norris's role in the first two films is much the same as her role in the books. She also appears briefly in the third film and in the fourth and fifth films she, along with Filch, are used more as comic relief. In the fourth film, Argus Filch is seen dancing with her at the Yule Ball showing a brief sensitive side to Filch and showing his love for his cat, and on the fifth film Mrs Norris is seen climbing on Filch during the Welcoming Feast, while he is clapping enthusiastically at Dolores Umbridge's speech. She has significantly more screen time in the final movie; Filch carries her as he runs into the Great Hall screaming that the students are out of bed, as well at the end of the movie, where she is comically sitting next to a pile of rubble as Filch attempts to sweep.
- In the earlier films, Mrs Norris has red eyes. In later films, however, she has blue eyes. Also, in the films, Mrs Norris has brown and grey fur.
- The cat that played Mrs Norris is a Maine Coon. In sharp contrast to Mrs Norris's description in the books as being scrawny, Maine Coons are a large, stocky breed.
- Several animal actors portray Mrs Norris throughout the films. The most notable include Maine Coons named Maximus, Alanis and Cornilus, and animatronics were also used. Specific animal actors were used for specific purposes. Maximus was trained to run alongside Filch and jump onto his shoulders, while Alanis was trained to be held in Filch's arms without squirming. She was so good at her job that often she fell asleep during shoots.
- Rowling said she obtained the name Mrs Norris from a character in Jane Austen's Mansfield Park, who is similarly odious and is hanging around in the background a lot.
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