Cat

A cat (Felis catus) is a small predatory mammal from Earth. Individuals of this type are often kept as pets among Humans. When cats are happy, they purr. Examples of cats kept as pets include Spot, owned by Data, Neelix, owned by Reginald Barclay,  and Chester, owned by Liam Bilby and, later, Miles O'Brien. 

In 2267, the alien Sylvia demonstrated the power to assume the form of a cat. She accomplished this feat with the aid of a device called the transmuter, which was the one element of her wardrobe that did not change shape. 

In 2268, the Enterprise, on a mission in the 20th century, encountered Gary Seven, an agent of a benevolent alien power that interfered to prevent civilizations from destroying themselves. He was accompanied by a cat named Isis, who was more than she initially appeared to be. Exactly what she was remains a mystery. She was evidently capable of understanding Gary Seven, and of communicating with him in at least a rudimentary fashion, and she accompanied him wherever he went. 

In 2269, a landing party from the Enterprise, while visiting the Shore Leave Planet, encountered a mechanical manifestation of an abnormally massive cat. 

It is possible that Natasha Yar had a cat. She at least felt obligated to protect one while being chased by a rape gang, when she lived on the failed colony Turkana IV, which appeared in illusionary form when the Traveler inadvertently sent the USS Enterprise (NCC-1701-D) to the "edge of universe." 

In 2366, Young Jeremy used to play "Captain Patches" with a cat, pretending Patches was a captain flying through space. 

"Cat" was one of numerous words Miles O'Brien used due to his infection of the aphasia virus. 

In the anti-time future seen by Jean-Luc Picard, Data had amassed a diverse collection of cats while a professor at Cambridge University.

In the alternate reality, nearly a year after stardate 2259.55, after the USS Enterprise'' (alternate reality) was rechristened, Captain James T. Kirk asked Chief Engineer Montgomery Scott about the performance of the new warp core. Purrin' like a kitten, Captain. was Scott's response.''

Related or similar non-sentient species

 * Berserker cat
 * Betazoid cat
 * Capellan power-cat
 * Circassian cat
 * Earth cats
 * Bengal tiger
 * Mountain lion
 * Grishnar cat
 * Hara cat
 * Kryonian tiger
 * Tika cat
 * Razorcat

Fictional cats

 * Cheshire Cat
 * Krazy Kat

Related or similar sentient species

 * Caitians
 * Kzinti
 * Vedala
 * Cat woman (species unknown)
 * Two Starfleet officers seen in the Council chamber during (species unknown)
 * Feline Alien prisoner in Star Trek VI: The Undiscovered Country