Human sacrifice is the act of killing one or more humans as part of a ritual, which is typically intended to please or appease gods, a human ruler, public or jurisdictional demands for justice by capital punishment, an authoritative/priestly figure, spirits of dead ancestors, or as a retainer sacrifice, wherein a monarch's servants are killed in order for them to continue to serve their master in the next life. Closely related practices found in some tribal societies are cannibalism and headhunting. Human sacrifice is also known as ritual murder.