The term demigod (or demi-god), meaning half-god, is commonly used to describe mythological figures whose one parent was a god and whose other parent was human; as such, demigods are human-god hybrids. In some mythologies it also describes humans who became gods, or simply extremely powerful figures whose powers approach those of the gods even though they are not gods themselves.

Examples of demigods include the Celtic hero Cuchulain, the Sumerian king Gilgamesh (who supposedly was actually two thirds god), the ancient Germanic woodsman Ansel and the Greek hero Heracles (Roman Hercules).

Part of the dual nature of Greek heroes that gave rise to the modern demigod conception of them is that one parent is a mortal, and another is a god. This scenario is also occasionally embellished with the theme of double paternity: the hero's mother lying with king and god in the same night (the mother of Theseus, for example) or to be visited secretly by the god (like Danaë, mother of Perseus), and the seed of the two fathers is mixed in her womb. Thus the heroes have liminal qualities that enable them to have great strength, to cross the threshold between the worlds of the living and the dead yet return safely, and to mediate long after their death between human and divine.