Fat Cat is a felonious gray Tabby cat and one of the Rescue Rangers most frequent antagonists. He was introduced as the pet of the nefarious underworld crime lord, Aldrin Klordane. Though Fat Cat presumably respects him, he continues his life as an independent agent and animal world crime boss after Klordane's incarceration. Enormously proud of his appearance, Fat Cat keeps his whiskers clean. When in the presence of humans, he displays very catlike traits (albeit a tad on the snooty and pampered side), but when with other furries, he wears a purple coat over a blue vest, a black dress shirt, and a red tie, and has a taste for expensive things. He is a relentless criminal mastermind, and his plans, though sometimes quaint, are nonetheless risky and merciless. Fat Cat despises dogs and several of his schemes have been attacks against them. The only thing he despises more than dogs are the Rescue Rangers, which he tries to get rid of using an elaborate and slow method at all times, rather than killing them at once. The complexity of his plots typically ends up being his downfall. He has a cousin who lives in Paris.
Fat Cat is normally accompanied by his four henchmen (Wart, Mole, Mepps, and Snout). Despite their combined foolishness, Fat Cat almost sends the four of them out to do his dirty work for him all the time, as he is too brainy or too work-shy to dirty his paws himself.
Fat Cat is a recurring threat to law and order as it applies to both humans and domestic animals, and to the Rescue Rangers. Chip, Dale, Gadget Hackwrench, Monterey Jack, and Zipper have outsmarted him and his thugs on numerous occasions.
During the original run of Rescue Rangers, Fat Cat made regular appearances at the Disney theme parks. His most notable appearance was in the Disneyland stage show The Disney Afternoon Live!: Plane Crazy, in which he and Don Karnage join forces and steal the X-22 spy plane. As a running gag, Don Karnage continually addresses him as "Cat Fat" by mistake throughout the show. After the initial run of the show and The Disney Afternoon, Fat Cat has not made any appearances at any Disney Parks and is now retired.
- His name may be a pun on the slang term "Fat Cat", meaning a wealthy and powerful person.
- He bears a minor resemblance to Mad Cat from Inspector Gadget.
- In Frank Angones' unproduced reboot of Chip 'n Dale Rescue Rangers, Fat Cat would have tried to carry away a plan from Professor Ratigan to destroy humanity.