Spot, loyal friend of Data, is a bit of a mystery.
First off, despite her name, Spot actually has no spots at all! She’s a bit of a gender-bender too. She originally appeared as a male Somali cat, but later manifested as a female orange tabby house cat, eventually giving birth to kittens (TNG: “Genesis”). These inconsistencies can be explained as Spot was the victim of a transporter accident.
Data looked after Spot well of course, he created several hundred food supplement variations for her and composed the poem “Ode to Spot” in her honour. (“Schisms”). A computer error occured later in the series (in the episode “A Fistful of Datas”) causing some of the ship’s food replicators to create only Spot’s supplements and replaced portions of a play with the ode’s text. Them’s the breaks.
Spot is notoriously unfriendly to most people other than Data. Commander Riker once received serious scratches while trying to feed her (“Timescape”). Seriously, you can’t be nice to everyone. However, she does get along with Lieutenant Reginald Barclay, so when Data had to leave on a mission at the same time Spot’s kittens were due, he persuaded Barclay to take care of her (“Genesis”)
Spot, you’ll always be a hero of mine.