Osiris was the god the ancient Egyptians associated with death, resurrection and fertility. He is depicted as a mummiform human figure with the royal regalia, the crook and the flail, in his hands and with the atef-crown, a white crown with a feather on either side and sometimes the horns of a ram, on his head.
In the Ennead of Heliopolis he is the son of Geb and Nut and the brother of Isis, Nephthys and Seth, he and Isis also being the parents of Horus. The most coherent story concerning Osiris is that told by the Greek author Plutarch. According to him, Osiris was a mortal king whose good rule evoked Seth's jealousy. During a party, Seth announced that he would present a chest (i.e. a coffin), which had been made using Osiris's measurements, to whoever fitted into it perfectly. Osiris stepped into the chest, upon which Seth locked it and threw it into the Nile. The chest floated to Byblos where it landed and a tree grew up over it. However, Isis found the chest and brought it back to Egypt where she wanted to bury her husband. Seth discovered this and cut Osiris' body into pieces and scattered them throughout Egypt. Isis then searched for all the pieces and buried each where she found it. Not all elements of this tradition are known from earlier Egyptian sources, though some may be found in texts from as early as the Old Kingdom. Seth is only named as the murderer of Osiris for the first time during the Middle Kingdom. An important difference between the tradition of Plutarch and the Egyptian sources is that in the former Horus was already alive, whereas the Egyptian tradition relates that Horus was conceived after Isis had gathered the body parts together into a mummy and had reanimated it by blowing the breath of life into it with her wings.
Osiris was worshipped from a very early period. It is assumed that he was originally a fertility god, whose duty it was to ensure a good harvest; as such he was related to the Nile inundation. It is for this reason that his skin is sometimes depicted as being green.
He quickly became the god of resurrection too. In the Old Kingdom, the deceased king was identified with Osiris, and his successor the living king with Horus. Later, as is demonstrated for example by the Coffin Texts and the Book of the Dead, every deceased person was considered to be an Osiris. Nevertheless, there exists in the Pyramid Texts of the Old Kingdom a slightly negative attitude towards life in Osiris's underworld. A continued existence in the sky, together with the sun god Re, was considered to be the ideal. In later centuries the two 'destinations' would become more aligned through the process of syncretism of the two gods, Osiris being regarded as the nocturnal aspect of Re.
The main cult centre for Osiris was Abydos, where the head of Osiris was purportedly buried which is also depicted by the nome emblem of the city. Other cities were also associated with the body parts of Osiris, such as Busiris which was associated with the backbone of Osiris, as represented by the ‘djed-pillar'. Near Memphis, Osiris was also associated with the mortuary god Sokar and with Ptah. Among his epithets, two of the most common are Wenennefer and Khentyamentiu, the latter actually the name of the original god of Abydos whose cult was early amalgamated into and superseded by that of Osiris.