Samhain is an ancient Celtic-pagan tradition, held in modern times from October 31 until November 1 to celebrate the harvest and welcome the changing of the seasons.
Spirits were thought to take different shapes around this time of year due to repeated sightings of Lady Gwyn, a headless woman dressed in white who would chase any who chose to wander at night, often accompanied by a black pig.
And sightings of Dullahan, a headless rider, usually on a black horse, who carries his own head on his arm. He calls out a person's name, drawing away the soul of his victim, at which point the person immediately drops dead.