The Dullahan (pronounced DOOL-a-HAN) - also referred to as the Headless Horseman - is a type of Fae originating from Irish folklore. This sinister being appears as a man or a woman riding upon a black horse, but the rider has no head upon their shoulders. Typically, the Dullahan carries its head under its arm; the head appears dead and rotten (sometimes compared to having flesh resembling old cheese) with a demonic grin spread across its face from ear to ear.
The Dullahan carries a whip made from a human's spine. Sometimes pulls wagon which 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 and when a Dullahan calls out the person's name, 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 however frightened of gold, and even a single gold pin can drive a Dullahan away.
The Headless Horseman of Sleepy Hollow
The Headless Horseman of Sleepy Hollow is a monster inspired by the Dullahan legend who appears in Washington Irving's 1820 Gothic short-story The Legend of Sleepy Hollow. In this story which is arguable the most famous incarnation of the Dullahan legend, the Headless Horseman is a ghost rather than a faery.
In the backstory given to the story, the Headless Horseman was a Hessian horseman (likely a mercenary) who fought for the British during the American Civil War. The Horseman was killed in 1776 at the Battle of White-Plains (although the book refers to it as "Some nameless battle") when his head was blasted off of his shoulders by a cannon-ball. They buried the body of the horseman in the graveyard of the Old Dutch Church outside a small dutch-colonized village called Sleepy Hollow (or "Tarrytown" in real life). According to the folklore of Sleepy Hollow, the ghost of the horseman emerges from his tomb at night and rides through the woods in search of his head own head or at the least, a new one.
According to legend, the Headless Horseman rises every night searching for his head, and if not, he would take someone else's. Ichabod Crane, Sleepy Hollow's school teacher, was first introduced to the legend when Brom Bones told everyone at Baltus van Tassel's Halloween party about the Horseman. That night, when Ichabod traveled back to Sleepy Hollow, he has a terrifying encounter with the Headless Horseman, resulting in the Horseman throwing his pumpkin head at Ichabod. What happened to Ichabod is unknown; he may have survived, or the Headless Horseman took his head. However, Brom Bones was the one behind Ichabod's chase and the legend itself. Ichabod's whereabouts following the event have remained a mystery.