Dullahan

The Irish dullahan (also Gan Ceann, meaning "without a head" in Irish) is a type of unseelie fairy.

Mythology
The dullahan is a headless rider, usually on a black horse who carries his or her own head under one arm. Usually the dullahan is male, but there are some female versions.

The head and the mouth is usually in a hideous grin that touches both sides of the head. Its eyes are constantly moving about, and can see across the countryside even in the darkest nights. The flesh of the head is said to have the color and consistency of moldy cheese.

The dullahan uses the spine of a human corpse for a whip, and its wagon is adorned with funeral objects. When the dullahan stops riding, that is where a person is due to die. The dullahan calls out the person's name, at which point the person immediately perishes.