Dullahan a Scary Fairy
The Dullahan fairy rampages about the countryside on festival/feast days. He is a headless horseman but carries his head in his hand. The head glows and can be used to light the way.
The head can only speak once on a journey and does so to call out the name of the soul it is out to collect. The Dullahan is different from the Banshee because the Banshee follows certain families and forewarns of death. The Dullahan brings the fact of death. Some say the Dullahan is the legacy of the time when beheading was an acceptable form of sacrifice to the gods and represents the remains of the Celtic god Crom Dubh (or Black Crom).
There is really no way to avoid encountering this fairy if you are the one sought. He can go anywhere and go rapidly. However, to avoid encountering him, stay indoors with the curtains drawn (if you look at him and you are not the one sought, you may be blinded or worse). Some believe that he fears gold so always have a bit of gold on hand on festival/feast days.