The Headless Horseman a ghostly rider can be found wondering roads outside cities seemingly randomly (Northwestern Skyrim around Dragon Bridge). He can not be interacted with although wolves along the road may try to attack him. When highlighted ,the option to talk to him appears but yields no dialogue; On a rare occasion he will say "Finality" or "Such an abrupt end to our journey". Follow him on a long journey to Hamvir's Rest where he will disappear in a graveyard where several skeletons will attack you. There is a Master Lock chest there that yields a random treasure.