Legendary Irish Headless Horseman

Word Meaning:

DULLAHAN — (fantasy, Irish mythology) A black-clad (usually male) horserider in Irish folklore which carries its severed head like a lantern and may be repelled by gold; when it stops riding (or calls out someone's name), someone will die. (Also called the Gan Ceann, Irish for "[one] without a head".)

Definitions from Wiktionary.