Cats are the clever kind of elil. They are stealthy hunters and pounce out of the shadows onto any rabbit without warning. They speak Lapine and they also follow the Lapine philosophy (like every other land animal, except for dogs). In Lapine, cats are called pfeffa.
The cat, Tab appears when the Watership Down rabbits come to rescue the hutch rabbits. He also attacks Hazel during the battle with Efrafa when Hazel and Dandelion come to find Bob. Lucy saves Hazel from the cat. Overall, there are not many cats in the story.