The Crazy Old Cat Lady is an old woman who lives with thousands of black and white cats. She is an exaggeration of the common archtype of an old woman owning several cats. The Crazy Old Cat Lady herself is catlike in appearance and behavior. She loves her cats very much, and calls them "her babies." Her bond with her cats is so strong that she possesses the power to control them and can order them to attack enemies when threatened. In extreme situations, the cats form together into the shape of a giant cat around her, which she directly controls. She is voiced by Grey DeLisle.
The Crazy Old Cat Lady is considered a particularly dangerous villain, and is usually referred to by Sector V simply as "her". She and her cats are especially threatening to the KND's Hamster allies. Crazy Old Cat Lady first appeared in Operation: C.A.T.S. as the main villain of the episode, and also has notable roles in Operation: F.L.U.S.H., where she is one of the villains who invade the Sector V Treehouse and are attacked by the Toiletnator, Operation: F.I.S.H.Y., where she and her cats attempt to take Numbuh 3's dead goldfish, and Operation: R.E.C.R.U.I.T., where the Interesting Twins From Beneath the Mountain, using the Bobby Costume, encounter her during their "test".
- Crazy Old Cat Lady seems to be based on Eleanor from The Simpsons.