The Fox is a small wild wolf-like mammal that is known as elil to rabbits, rodents, and cats. They are often described as stinking (embleer) by the rabbits. The Lapine word for fox is "homba".
Also, shortly after the Down rabbits and the Efrafan fugitives escape from Efrafa, the same fox ambushes them and snatches one of the does.
In the television series, foxes appear as minor antagonists.
- In "The Easy Life," a fox appears and sneaks towards Cowslip's warren, but is shot and killed by a man.
- In "The Challenge to Efrafa," a fox sniffs out Hazel and his Owsla on their trek to Efrafa and gives chase to them. Bigwig then leads the fox away from the others, and runs into Gorse and Thistle. The fox then bursts from the bushes and leaps upon Gorse and Thistle, killing them both, while Bigwig escapes.
- In "Escape From Efrafa," the same fox is sniffing around and follows the rabbit scent to the perimeter of Efrafa. It then notices the skull of another fox that was placed at the entrance and the carnivore walks away from the warren. It is later mentioned by Campion to Bigwig that a fox had tried to attack Efrafa the previous season when it was looking for an easy meal, but was killed by General Woundwort and his Owsla. Its skull was then left at the warren's entrance as a warning to other invaders of Efrafa's power.
- In "The Market," a female fox unexpectedly attacks Hazel, Fiver, Bigwig, and Hawkbit without a warning from Kehaar, who has flown off to try to talk with a flock of birds from his homeland. After chasing Hazel, she loses him and the rabbits quickly escape, not wanting to give the fox a second chance.
- In "Winter on Watership Down, Part 1," the female fox returns as the main antagonist and attacks Hazel, Fiver, Bigwig, Hawkbit, and Dandelion while they are looking for food for Frith's Eve. She is temporarily driven away when Kehaar attacks the carnivore while it is standing on a frozen lake that was ready to crack. However, the fox appears again and watches the rabbits walk into the distance while helping a freezing Bigwig get warm, and proceeds to follow them, intent on having them as a meal during the winter season.
- In "Winter on Watership Down, Part 2," the same female fox follows the scent of Hazel and his group and stalks them into the maze that contains Buttercup's warren. When it sees Hazel, Fiver, Dandelion, and Hawkbit in the maze, the carnivore chases after them until she is frightened away by the presence of humans who are surrounding Buttercup's warren singing Christmas carols.
- A fox appears briefly in "The Secret of Redstone," lurking around and hunting for the rabbits in Redstone Warren, before being scared off by the sound of a gun.