a supreme ruler, sovereign over a nation or a territory, of higher rank than any other secular ruler except an emperor, to whom a king may be subject. Kingship, a worldwide phenomenon, can be elective, as in medieval Germany, but is usually hereditary; it may be absolute or constitutional and usually takes the form of a monarchy, although dyarchies have been known, as in ancient Sparta, where two kings ruled jointly. The king has often stood as mediator between his people and their god, or, as in ancient Sumer, as the god's representative.

Sometimes he himself has been regarded as divine and has become the key figure in fertility rituals; such religions often ultimately required the death either of the king himself or of an official substitute as a sacrifice to the gods. The concept of divinity, brought in from Egypt, characterized the Hellenistic Age, and was later revived by the Roman emperors. The Christian Roman emperors assumed authority as representatives of God, and, in medieval political theory, kingship was early regarded as to some extent analogous with the priesthood, the ceremony of anointing at the coronation becoming highly significant. The absolute monarchies of the 16th to 18th century were often strengthened by the establishment of nationalist churches; but from the 17th century in England and, later, in other countries, kingship was made constitutional, royal power being held to derive from the people rather than from God.