Osiris was the Ancient Egyptian god of the dead, and the god of the resurrection into eternal life; ruler, protector, and judge of the deceased. His cult originated in Abydos, where tradition locates his tomb.

Osiris was the first child of Nut and Geb, and brother of Set, Nephthys, and Isis, who was also his wife. By Isis he fathered Horus. Some variations on the legends say that Nephthys assumed the form of Isis in order to seduce Osiris, whereby she bore Anubis.

Osiris ruled the world of men after Ra left the world to rule the heavens. He was murdered by his brother Set, who later dismembered his body and scattered the remains. The grieving Isis reassembled the parts and magically brought him back to life. Since he was the first living thing to die, he subsequently became the lord of the dead. His death was avenged by his son Horus, who defeated Set and cast him out into the Western Desert.

The cult of Osiris persisted throughout Egyptian history. Funeral texts address numerous prayers and spells in hopes of securing his blessing upon entering the afterlife (e.g, the hymns in The Egyptian Book of the Dead are primarily addressed to Osiris). His popularity steadily increased through the period of the Middle Kingdom, and endured into the period of Roman rule. The Ptolemaic rulers of Egypt during Roman times continued his cult, even to affecting the traditional clothing of the Pharaohs and making offerings to him in the temples.

The Tale of Isis and Osiris is one of the enduring classics of Egyptian mythology, embracing many themes that were to reappear in countless stories throughout the ancient world. The episodes recounted in the tale have led many scholars to suggest that Isis and Osiris are deifications of historical persons; ancient ancestral rulers who brought civilization to the peoples of the Nile valley, gave them their laws, and taught them the arts of civilization (among them the making of bread and wine; the people already knew how to make beer).