Cat

Cats are creatures seen in Fallout 2, Fallout: New Vegas, Fallout 4, Fallout 76, and Fallout Shelter.

Background
Cats are a species of small predatory carnivorous animals that were valued by humans before the Great War for their companionship and ability to hunt vermin, such as rodents, snakes, scorpions, and other household pests.

After the Great War, many cats in what used to be the United States were hunted for food because they were easy prey. Although not as common as before the Great War, domestic cats still survive as seen in the Commonwealth.

Fallout 2

 * Stacy, a resident of the Den in 2241, used to have a cat called Cuddles as a child that was killed for food.
 * A man in Broken Hills mentions his pet cat.
 * The Shark Club comedian makes a joke about Super mutant trying to get a cat out of a tree.

Fallout: New Vegas

 * A cat can be seen in the slideshow in the sacrificial chamber in Vault 11.

Fallout 4

 * Two cats can be found in Catherine's room in Sandy Coves Convalescent Home.
 * A cat named Toro can be found in the schoolhouse in Diamond City.
 * A cat called Emmett can be found next to Proctor Quinlan's desk on the Prydwen.
 * Several house cats can be found directly south of Gorski cabin, along with a trader selling cat meat at Walden Pond.
 * There are a large number of cats in the Hawthorne residence in the upper stands of Diamond City.
 * Dora can be found in the town of Covenant.
 * There is a grey house cat found inside of Sleepwalker's place.
 * There is a cat named Maisie lounging around the house entrance of Abernathy farm.
 * There is a cat near the trader's shack, west of the Ranger cabin.
 * There's a single cat in South Boston Church in front of a cat altar.
 * Inside Vault 81, there is a cat called Ashes that belongs to Erin Combes.
 * A gray cat can be found in the shop, Mean Pastries, in the vicinity of Pickman Gallery.
 * There is another house cat in the cottage near Pickman Gallery.
 * Mr. Pebbles is mentioned in posters as being the first cat in space.
 * Three cats can be seen following a veterinarian Mister Handy in a random encounter.
 * Multiple dead cats can be found inside the Institute FEV lab.

Fallout 76
Cats return in Fallout 76, as either unique ones or a generated cluster of three level 1's with their name being different breeds, tabby being house cat.
 * A cat named Cheswick can be found at the Wixon homestead.
 * Generic cats can be reliably found between 98 NAR Regional and Maybell Pond.
 * Two can be found in Scoot's shack, to the south of the Southern Belle Motel.
 * One can be found at the billboard to the west of Beckwith farm on the edge of a cliff.
 * Murgle claims a coffee hut in the Mount Blair region, directly between Mount Blair trainyard and Welch station. A painting on the counter may or may not be of Murgle that the cat sits and meows at.

Fallout: Brotherhood of Steel
Mr. Pussy, a domestic cat, died in Carbon, Texas in 2208. Ruby the prostitute wanted to find him when he got lost, and asked the Initiate to help. They discovered the cat's corpse in the carbon crater and brought it back to Ruby.

Van Buren
According to the Nursery design document, various cats were to make an appearance there. There would have been friendly domestic cats kept by humans, as well as wildcats, bobcats and panthers that were hostile to the player.

Related quests

 * Listen to Stacy's kitty story
 * Here Kitty, Kitty
 * Someone to Talk To