Osiris — Egyptian Wesir — is the son of Geb (earth) and Nut (sky), brother of Set, Isis and Nephthys, husband of Isis, and father of Horus. He was the first divine king of Egypt — the god who civilised humanity by teaching them agriculture, law and the worship of the gods, before being murdered by his jealous brother Set and becoming lord of the underworld and judge of the dead.
His appearance is among the most distinctive in Egyptian art: green or black skin (green representing vegetation and resurrection; black representing the fertile Nile silt), wrapped in white mummy bandages from the chest down, wearing the Atef crown (a white crown flanked by ostrich feathers), and holding the crook and flail — the symbols of Egyptian kingship. He is both the most alive and the most dead of gods: alive because resurrected, dead because mummified. His green skin is the colour of spring growth emerging from dark soil — life from apparent death.
In Egyptian theology, Osiris occupies a unique position. He is simultaneously the dead pharaoh (every pharaoh upon death became Osiris, just as his successor became the living Horus), the grain (which is cut down, planted in the dark earth and rises again), the Nile (which floods, recedes and floods again), and the moon (which wanes to apparent death and waxes to renewed fullness). He is the principle of cyclical renewal through death — the force that ensures nothing is truly lost, that everything that dies returns in a new form.
The Pyramid Texts — the oldest religious corpus in the world — are substantially concerned with identifying the dead pharaoh with Osiris and ensuring his resurrection. The phrase "Osiris N" — where N is the name of the deceased — became the standard formula in Egyptian funerary texts, extended by the Middle Kingdom to non-royal Egyptians. Every Egyptian who died, properly prepared and judged worthy, became Osiris. Osiris democratised immortality — what had once been the exclusive privilege of the pharaoh became, over centuries, available to all who lived rightly and performed the proper rites.