Human sacrifice was a rare practice among the cultures of ancient Mesopotamia. Our best-sourced occurrences are the archaeological remains from the royal death pits at Early Dynastic Ur (c. 2600–2450 BCE) and textual records of the substitute king ritual that was practised at least from the early second millennium BCE down to the time of Alexander the Great. Such sporadic occurrences of ritual human sacrifice require an investigation as to why it happened at all. This chapter examines the practice of human sacrifice in the light of its respective historical and cultural contexts to better understand this extreme form of ritual violence. It finds that while there are rather different contexts, in both instances it is clear that the office of kingship held absolute power over the subjects who were disposed of for the sake of the ruler.