Ra – Sun
Ra or Re is the ancient Egyptian deity of the sun. He was believed to rule in all parts of the created world: The sky, the Earth, and the underworld. By the Fifth Dynasty in the 25th and 24th centuries BC, he had become one of the most important gods in ancient Egyptian religion, identified primarily with the noon sun.
In later Egyptian dynastic times, Ra was merged with the major god Horus into Ra-Horakhty (“Ra, who is Horus of the Two Horizons”). He was synonymous with the falcon, and he was commonly depicted with the head of a falcon. These images can be told apart from images of Horus due to having a sun disk on its head instead of Horus’s usual Pschent headdress.
When Ra was in the underworld, he merged with Osiris, the god of the dead, and through it became the god of the dead as well. He was most commonly featured with a ram’s head in the Underworld. In this form, Ra is described as being the “ram of the west” or “ram in charge of his harem.
Osiris – the underworld, and rebirth
Osiris was at times considered the eldest son of the god Geb and the sky goddess Nut, as well as being brother and husband of Isis, with Horus being considered his posthumously begotten son.
He was also associated with the epithet Khenti-Amentiu, meaning “Foremost of the Westerners”, a reference to his kingship in the land of the dead. As ruler of the dead, Osiris was also sometimes called “king of the living”: ancient Egyptians considered the blessed dead “the living ones”.
Osiris was the judge of the dead and the underworld agency that granted all life, including sprouting vegetation and the fertile flooding of the Nile River. Through the hope of new life after death, Osiris began to be associated with the cycles observed in nature, in particular vegetation and the annual flooding of the Nile, through his links with the heliacal rising of Orion and Sirius at the start of the new year.
The Kings of Egypt were associated with Osiris in death – as Osiris rose from the dead so would they in union with him, and inherit eternal life through a process of imitative magic. By the New Kingdom all people, not just pharaohs, were believed to be associated with Osiris at death, if they incurred the costs of the assimilation rituals.
Horus – Mars
Horus served many functions, most notably being a god of kingship and the sky. The earliest recorded form of Horus is the tutelary deity of Nekhen in Upper Egypt, who is the first known national god, specifically related to the ruling pharaoh who in time came to be regarded as a manifestation of Horus in life and Osiris in death.
The most commonly encountered family relationship describes Horus as the son of Isis and Osiris. In another tradition Hathor is regarded as his mother and sometimes as his wife. He plays a key role in the Osiris myth as Osiris’s heir and the rival to Set, the murderer of Osiris.