The dullahan is a headless rider, usually on a black horse who carries their own head under one arm. The head's eyes are small, black, and constantly dart about like flies, while the mouth is constantly in a hideous grin that touches both sides of the head. 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 (e.g. candles in skulls to light the way, the spokes of the wheels are made from thigh bones, the wagon's covering made from a worm-chewed pall or dried human skin). 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.
There is no way to bar the road against a dullahan—all locks and gates open to them when they approach. They do not appreciate being watched while on their errands, throwing a basin of blood on those who dare to do so (often a mark that they are among the next to die), or even lashing out the watchers' eyes with their whips. They are frightened of gold, and even a single gold pin can drive a dullahan away.
In popular culture
In the light novel series Durarara!! and the anime series based on it, the character Celty Sturluson is a Dullahan from Ireland who came to Japan searching for her head and lost memories. She is portrayed as an immortal woman without a head and has supernatural powers, with a familiar who takes the form of a black motorcycle.
An adaptation of Dullahan also appears in the portable video game Golden Sun: The Lost Age. Here, the being is an optional boss as well as the strongest enemy in the entire game. It appears as a suit of armor without a head; the being guards the imprisoned tablet of Iris, the Sun Goddess, one of the strongest summons in the game. It reappears in Golden Sun: Dark Dawn, filling the same role.