Osiris is one of the most important gods of ancient Egypt. He was originally a local god of Busiris, in Lower Egypt, and may have been a personification of chthonic (underworld) fertility. However, by about 2400 BCE, Osiris clearly played a double role: he was both a god of fertility and the embodiment of the dead and resurrected king. This dual role was in turn combined with the Egyptian concept of divine kingship: the king at death became Osiris, god of the underworld; and the dead king’s son, the living king, was identified with Horus, a god of the sky. Osiris and Horus were thus father and son.

Osiris is the god of fertility, agriculture, the afterlife, the dead, resurrection, life, and vegetation in ancient Egyptian religion. He was considered the master of the underground world, the next world – the Afterlife. His wife and sister was Isis, goddess of motherhood, magic, fertility, death, healing, and rebirth. The goddess Isis was the mother of the king and was thus the mother of Horus and consort of Osiris. The god Seth was considered the murderer of Osiris and adversary of Horus.

The idea that rebirth in the next life could be gained by following Osiris was maintained through certain cult forms. In the Middle Kingdom (1938–c. 1630 BCE) the god’s festivals consisted of processions and nocturnal rites and were celebrated at the temple of Abydos, where Osiris had assimilated the very ancient god of the dead, Khenty-Imentiu. At Memphis, the holy bull, Apis, was linked with Osiris, becoming Osiris-Apis, which eventually became the name of the Hellenistic god Serapis. Greco-Roman authors connected Osiris with the god Dionysus.