Cats are a group of monsters comprised of wild cats, cave lions, and cave tigers.

In order to receive the powerful ring of the master cat, the PC must not kill any cats until he talks to the cat lord, who is located on D:35 or D:36. If the player succeeds, the cat lord will commend him for respecting the cat race, grant him the ring, and then disappear. If the PC has killed cats, the cat lord will instead be generated as uncaring or hostile. The more cats that have been killed, the stronger the cat lord will be, and the more likely that he will start out hostile.

When killing a cat, a there may be a message about the cat's spirit rising and then plunging into the ground. Whether or not it shows up is based on a Perception check, and it is only displayed once per game. The message does not have any special significance for the cat lord's disposition.

The player can use a number of tactics to avoid killing cats. Only PC kills count, so companions, floor traps (including from wand of trap creation), enemy breath attacks, and vortex explosions can be used to safely dispose of cats. Cats can be avoided with high speed, closed doors, digging, and teleportation. Cats can be tamed with music, meat, and sometimes rat corpses. Another approach would be to transform cats using potions of exchange, potions of raw chaos, or corruption traps.

Two of the first 20 Arena fights have a chance of generating a cat as an opponent. Spellcasters can teleport cats out of the arena, thus winning the fight without killing the cat.