The archetypical pet for Shrinking Violet or loner characters is the domestic cat. An introverted character will often also be a Kind Hearted Cat Lover. Oftentimes the cat(s) are a replacement for human interaction, or in the case of lonely single women, lovers and occasionally children.
The popularity of this trope likely occurs because cats, in contrast with dogs, are an inside pet. They don't require walks and can live their entire lives inside. As a result, they're great for people who dislike going outside. This also applies to other pets such as birds, small rodents, and reptiles, however those rarely appear in fiction (and when they do they're usually owned by "weird" characters).
This person might get called a Crazy Cat Lady, and might develop into one as they get older, but the difference is that a Crazy Cat Lady has a mental illness, while (most) Introverted Cat People do not.
The feline counterpart of Canine Companion. Contrast with Heroes Love Dogs, which this trope tends to be a foil to (with more extroverted characters preferring dogs). Related to Right-Hand Cat if the evil boss is Lonely at the Top. Super-Trope to Crazy Cat Lady.
- An [adult swim] bumper mentions that the viewer is lonely and friendless, except for their pet cat Whiskers.
- Quiet Shrinking Violet Sakaki from Azumanga Daioh adores cute animals in general, but she has a special spot in her heart for cats. Unfortunately, cats don't like her (with Word of God being that her intimidating looks makes cats afraid of her).
- Ichimatsu from Osomatsu-san is the quietest of the sextuplets. Ichimatsu isn't fond of socializing with others. He adores cats and is most social around them (though some jokes imply his interest in cats isn't exactly chaste).
- Suzuka from Lyrical Nanoha is the resident Shrinking Violet among her friends, and her mansion is full of cats. Contrast with her far more outgoing best friend Arisa, who is a dog person.
- Kaoruko of Comic Girls is excessively shy, fragile and negative, and on the other hand she likes cats so much that the fact that her new apartment does not allow pets left her with cat withdrawal.
- As one more showcase that she is Not Good with People, Doctor Ritsuko Akagi of Neon Genesis Evangelion has a pet cat and cat-themed office furniture in her lab.
- My Roommate is a Cat: Subaru is introduced as so introverted he actively avoids people and even leaving his house unless strictly necessary. The story starts with him taking in a stray cat.
- Shota Aizawa of My Hero Academia is a grumpy, unkempt underground hero who can often be found teaching his class from inside a sleeping bag. Vigilantes shows him with a shopping bag full of cat food and cat care books, and Smash!! actually pits him against two of his students in taming a stray cat for a final exam. He's the happiest the audience has ever seen him.
- Ami Mizuno, in Sailor Moon, is a shy bookworm who doesn't make friends easily. According to her official bio, cats are her favorite animal, and she's often seen petting and cuddling with Luna.
- Adrian Veidt, aka Ozymandias, from Watchmen is Not Good with People and prefers the company of Bubastis, his genetically-engineered lynx.
- In Neither a Bird nor a Plane, it's Deku!, Katsuki Bakugou has a blue cat named Dexter who is about as prone to rage as his owner is (don't worry, he's not a Red Lantern). The cat seems to be one of Katsuki's only meaningful relationships, as he looks down on everyone else who isn't Izuku.
- In Ariel & Belle, Belle keeps to herself and is unable to socialize well with her fellow townsfolk. Her main companion is her pet cat, Cheeky.
Film — Animated
- The socially awkward protagonist of Atlantis: The Lost Empire, Milo, has a pet cat named Fluffy. Fluffy is Milo's only companion at the start of the film.
- Madame Adelaide from The Aristocats is an old rich woman who mostly spends time with her titular cats.
Film — Live Action
- In Romancing the Stone, Joan Wilder is a successful romance novelist, but has no romance in her own life. She celebrates special events with her cat, Romeo.
- In Batman Returns, Catwoman is portrayed as a socially awkward introvert whose cat is her best friend.
- In Wonder Woman 1984, Barbara Minerva is portrayed pretty much like Selina above, as in socially awkward and wearing Nerd Glasses; before she turns into Cheetah.
- Erin, the perpetually-ignored file girl in What Women Want, has a cat, which Nick discovers when he goes to her apartment to Must Make Amends when he overlooked her for a promotion.
- Filch from Harry Potter and his cat Mrs. Norris. He's a Muggle Born of Mages with resentment towards wizards, who worked as a scary groundskeeper for Hogwarts; many students fear him.
- Hermione is an Extraverted Nerd, but she is still more introverted and bookish than her two best friends and gets her own cat Crookshanks in Book Three.
- Little Women: Beth is the shyest and quietest of the four sisters. Cats is one of the things she loves the most and she is often surrounded by kittens.
- The Baby-Sitters Club: Mary Anne, the Shrinking Violet of the group, has a pet cat named Tigger and constantly tells people how cute he is. By contrast, her brash best friend Kristy has a dog.
- In one of the Cat Pack books, Carlotta offers up her kittens to a local retirement home. The seniors there don't get to out much, so the kittens will help entertain them and keep them company.
- Desperate Housewives has two examples: Mr. Whiskers (Alberta Fromm's cat, seen only in season one) and Toby. The latter used to be Ida Greenberg's cat until she died in season 4, then Karen McCluskey took care of him. Season 5 Big Bad even lampshaded this trope, saying that Karen must be lonely since she talks to her pet cat Toby.
Karen: Toby is Ida's baby.
- Criminal Minds: Emily Prentiss lives with her cat, Sergio. Sometimes, she complains about her romantic life being boring or unsatisfying.
- Lilly Rush from Cold Case has relationships go down in flames more than once due to her devotion to work, but she always has her cats.
- Mentioned during a fight between Peggy and her mother in the fifth season of Mad Men. Her very Catholic mother is quite upset that Peggy is moving in with and not marrying a Jew. When Peggy asks if her mother wants her to be alone, she replies, "Your aunt used to say 'If you're lonely, get a cat'. It'll last fifteen years, then you get another cat. That'll last fifteen years, an then you're dead."
- In Hannah Montana, Miley imagines that future in her head.
- To show that Wonder Woman's Secret Identity Diana Prince is a friendless introvert, the Wonder Woman pilot ends with her watching television with her cat.
- Played with in the case of Sally and Mr. Henderson in The Dick Van Dyke Show. Sally is a brash woman, but she's also single and unhappy about it. At least one episode had her talking to Mr. Henderson about how neither of them had anywhere to go that evening.
- In Elementary, recurring character Fiona Helbron. She is a fairly asocial, neuro-atypical programmer who was a witness in the episode "Murder Ex Machina" and later became a love interest for Sherlock. She loves cats and once meets with Sherlock at a cat café (because she isn't allowed to keep pets at her apartment).
- Reg Barclay from Star Trek: The Next Generation is a painfully shy Shrinking Violet, as well as the only person that Data's cat Spot is on friendly terms with (besides Data himself). On Star Trek: Voyager, Reg gets his own cat, Neelix.
- The Twilight Zone (1985):
- In "The Trunk", Willy Gardner has no meaningful interaction with people as the manager of the rundown Hotel Winchester. The highlight of his day is giving a stray neighborhood cat a bowl of milk.
- In "Cat and Mouse", the shy, timid Andrea Moffatt is delighted when a black tomcat comes through her window one evening. It turns out that the cat is Guillaume de Marchaux, who was cursed to become a cat during the day and can only revert to human form at night.
- In the first few seasons of Sex and the City, Miranda lived alone with her cat, and she's by far the snarkiest, most aloof of the main characters. When she starts opening up and starts living with Steve, they also get a dog.
- Jon from Garfield is routinely portrayed as a friendless Loser Protagonist with No Social Skills. His main companion is his cat Garfield, with later his dog Odie being brought into the strip too. Though he wasn't always like this, Lyman kept him company from 1978 to 83 and then Liz came in and started dating Jon since 2006.
- In Fire Emblem Echoes: Shadows of Valentia, Luthier is a socially awkward nerd who protests the idea that he's never had any friends by bragging that he's gotten very close to a local cat.
- In Sakana, Yuudai, the angry loner who pushes away anyone who tries to get close, has his cat Hime serve as the one being that he openly loves.
- In Webcomic/Homestuck, out of the two girls, Rose is an introverted Goth with a penchant for psychoanalysis. Naturally she's a cat lover to contrast her best friend Jade, who has a dog.