Cait Sith is a talking toy cat who is friendly, but often unreliable. He rides on the back of a stuffed moogle, which does all of the pair's fighting. During Final Fantasy VII, Cait Sith is a cat that sits on top of a giant stuffed moogle, to which he gives orders by using a megaphone. In subsequent publications, he's usually been seen on his own two feet. As a somewhat cartoonish character, he quite noticeably stands out from the game's overall dark theme. His name is derived from Celtic folklore, meaning "Fairy Cat." Several models of Cait Sith exist. Known as "Stray" in the original English release of Final Fantasy VI (but changed back to "Cait Sith" in the GBA release), Cait Sith's current design initially appeared as an Esper in that title.
Cait Sith initially joins the party in the Gold Saucer. He joins after offering to use his abilities as a fortune teller to predict Cloud Strife's future. The prediction is a rather grim one, as he tells Cloud that he will find what he seeks but will also lose something dear, foreshadowing the ultimate fate of Aerith Gainsborough. He joins the party, arguing that he can't leave without knowing how this "rare fortune" will turn out. Later in the game, it is revealed that "Cait Sith" is actually an animatronic robot that is being controlled by remote by Reeve Tuesti, who is himself a reluctant member of the despotic Shinra's board of directors, where he serves as the head of the Department of Urban Development. Reeve's intent was to use Cait Sith to infiltrate AVALANCHE and sabotage their resistance efforts on behalf of his employers. When the team returns to the Gold Saucer to retrieve the Keystone required to gain entry to the Temple of the Ancients, Cait Sith's role as a spy becomes apparent, as he betrays the party by stealing the Keystone and handing it over to the Turks. However, Reeve has a change of heart, deciding that he wants to stay with the team and betray Shinra. Untrusting, Cloud refuses, but instead of getting kicked out of the team, he coerces them into letting him remain with them, revealing that Barret Wallace's adopted daughter, Marlene, is in his custody. Feeling that they have no choice, AVALANCHE agrees to allow Cait Sith to remain with them.
Later, in the Temple of the Ancients, it's revealed that to unlock its secret (the Black Materia), a mechanism inside the temple had to be activated. However, it's also discovered that activating it would cause the very structure to collapse upon itself, crushing anyone who attempted to retrieve the Black Materia. Cait Sith was willing to sacrifice himself, as he was just a stuffed toy and the most expendable member of the team. Cait Sith no.1's death is presented in a very dramatic fashion despite the fact that he was just a robot, but when looking further into the matter, it appears that Cait Sith does indeed have some sentience. Before he "dies," Aerith asks him to work his fortune-telling skills one more time to predict how compatible she and Cloud Strife were as a romantic couple. He comes to the conclusion that they are a perfect match, though it is never revealed what the fortune exactly read. He then leaves to solve the puzzle of the Ancients that unlocks the Black Materia, and eventually succeeds in unlocking the materia but is destroyed as the temple implodes. Before he dies, he asks everyone not to forget him, even if more Cait Siths come after he's gone. Moments later, however, another version of Cait Sith awkwardly arrives on the scene, hence completely negating any tragedy or sense of loss in the process.
Cait Sith appears in Episode 20 of Before Crisis: Final Fantasy VII to assist the Turks, while Reeve Tuesti (Cait Sith's controller) plays an overall small role in the game as architect of Midgar and director of Shinra's Housing and Urban Development Department. He rides on a stuffed MOG. Cait Sith makes a brief appearance in the latter half of Advent Children, fighting along with AVALANCHE when Edge is overrun by Shadow Creepers and attacked by Bahamut SIN. Square Enix has explained that the toysaurus moogle was cut due to the extra amount of work that would have been required to animate it. The creators notably point out that they already disliked animating both Cait Sith and Red XIII due to the level of detail required for their fur. Although the script in Final Fantasy VII didn't attempt to localize any of the character's accents or speech patterns, Advent Children does, and Cait Sith was given a Scottish accent. In Dirge of Cerberus, Cait Sith is the only character other than Vincent Valentine to be playable in the game, but for a short period of time. While Cait Sith retains the Scottish accent of Advent Children, his use of language does not include any Scottish slang or speech patterns, unlike the film. A reference to his small part in the plot is made by Yuffie in after a small skirmish with Deep Ground. Noticeably, Reeve never mentions Cait Sith by name and constantly refers to him with phrases such as "you-know-who". However, Cid speaks his first name in Dirge Of Cerberus during a conversation with Vincent.
Cait Sith, appearing as a Mascot costume, is a Dressphere used by Rikku in Final Fantasy X-2. In the video game Kingdom Hearts II, there is a gummiship called Cait Sith. It looks like Cait Sith from Final Fantasy VII. In the MMO "Final Fantasy XI" there is a world server known as Caitsith. In Final Fantasy X, Lulu can obtain several Cait Sith dolls to use as weapons, where they usually inflict status ailments on the enemies when attacking. In Final Fantasy Fables: Chocobo Tales Cait Sith appears on several cards used in the game's card battle system, as well as one of the main characters in one of the Storybooks of the game. In this game, his dialogue is written to match the Scottish accent he has been given in previous incarnations.