The vampiric spirit of the ovengua comes from Guinea, Africa. When an evil sorcerer dies, his bones will begin to escape from the grave one at a time and gather in a secret location. Eventually, when they have all come together, the bones will reassemble themselves and become an ovengua, a skeletal spirit being that has large hooks for hands. Hiding in caves by day and wandering the forests at night, the ovengua will attack any lone traveler it sees and try to possess the person. Should the ovengua win, it will kill the person and animate the corpse to use as its own. The only way to destroy it is, unfortunately, to wait until it has claimed a body — then capture it and burn it to ash.

Source: Du Chaillu, King Mombo, 79-83; Wood, Natural History of Man, 572; Wood, Uncivilized Races of Men, 513