Legends and lore, mostly, or things that can't be explained. People who were wrongfully killed or die before they could complete something, doomed to haunt the earth, extracting their vengeance on those who wronged them. Almost every culture in my world has some story or legend about ghosts or spirits.
[All fairly morbid sounding too, but they did make for good stories around a campfire or around Halloween.]
[Action]
[All fairly morbid sounding too, but they did make for good stories around a campfire or around Halloween.]