The god Osiris, ruler of the underworld, became famous as the central figure in a creation myth describing his death and resurrection, and was associated with the cult center of Heliopolis. In Old Kingdom Pyramid Texts, the pharaoh sought his own rebirth by identifying himself with Osiris. By the First Intermediate Period, this path to rebirth was available to all ancient Egyptians. Osiris was represented as a mummiform figure dressed in a white linen shroud; he was provided with royal crook and flail scepters, as well as distinctive crowns (symbolizing kingly status).
His skin was often colored green, connoting his role in the growth of plants and thus rebirth. Extending this theme of bringing forth new life, he sometimes was depicted with an erect phallus, miraculously restored by Isis after reconstituting his body.
Osiris' cult was principally based in Abydos, considered his burial-place. Abydos became a major place of pilgrimage; those who could visited Abydos at least during their lifetime. Tomb paintings depicted the deceased being transported to Abydos, and model boats were provided in tombs for the journey. The site of Abydos had been important since before the Early Dynastic Period (beginning ~ BCE) when the earliest kings were buried there.
The original local deity of Abydos was the jackal-god Khentimentiu, the Foremost of the Westerners (ie, the dead). Khentimentiu was absorbed into the Osirian cult as the latter gained importance. This resulted in the name Khentimentiu becoming an epithet for Osiris.
In some fo the Old Kingdom Pyramid Texts, the dead king is identified with Osiris and thereby was believed to experience rebirth just as the murdered god had done.