A Sylvan, also called willower or a deovel, is a humanoid, intelligent herbivore with goat's horns on its head, hairy legs with cloven hooves, and a tail with a tassel at the end. They're exceedingly rare. Their description was given in the short story The Edge of the World.
| The creature was about half a rod tall with bulging eyes and a goat's horns and beard. The mouth, a soft, busy slit, also brought a chewing goat to mind. Its nether regions were covered with long, thick, dark-red hair right down to the cleft hooves. The devil had a long tail ending in a brush-like tassel which wagged energetically.
— page 176, The Last Wish (UK edition)