The Kitten Catastrophe Crew are the titular secondary antagonists of the PAW Patrol episode "Pups and the Mischievous Kittens."
They are the villainous, non-speaking, feline counterparts of the heroic, speaking, canine PAW Patrol (except the newest, Everest, but that may be because he never knew Everest when he secretly adopted the six he had). Their owner is Foggy Bottom's Mayor Humdinger, and he uses them as a secret weapon to mess up Adventure Bay for Mayor Goodway. They would, for example, shoot balls of yarn (to Chase's allergy), rip off the flowers from the flower bed, and spill trash, and eventually, upon Humdinger's prompting, attempt to flood the town.
As punishment, the kittens and their master have to clean up Adventure Bay.
They appear again in "Pups Save the Mayor's Race" as secret weapons for Mayor Humdinger who cheats to beat his fellow mayors. First, Mayor Humdinger has Rocky's feline counterpart drill a hole in Mayor Goodway's rowboat so it will have a leak and she'll lose the rowboat race, but Zuma saves her, and the PAW Patrol fix it. In the rowboat race, he has Zuma's feline counterpart push his boat quickly. Then in the swimming race, he has Chase's feline counterpart shoot "sardines" that then become sardines to block the other mayors' path, and he swims through, claiming not to have time to play with dolphins. Then in the running race, he has the kittens pour corn oil, only for Chase to shoot his net over them, though they managed to pour a little corn oil; so all of the mayors keep running except Humdinger who then uses the cat carrier and tries taking a shortcut to win, only to fall into a hole and have to hold onto a branch, only to be rescued and then disqualified for cheating.