Osiris

Osiris is an Egyptian deity, who in his original form, was seen as a green-skinned man dressed in the raiment of a pharaoh.  He is often depicted wearing the atef crown with a pair of ram horns at its base. As the Egyptian god of the under world, he is seen as the judge of the dead. Linking him to the concept of Cernunnos as the guardian of the gate to the Other World. Throughout the height of Egyptian civilization, Osiris was the primary deity. In power, he was second only his father, Ra, and was the leader of the gods on earth. He was the husband of Isis and the father of Horus (and a number of other gods in some stories). Osiris resided in the underworld as the lord of the dead, as after being killed by Set, even though he was a god, he could no longer dwell in the land of the living.

After Osiris was killed, Isis resurrected him with the Ritual of Life, which was later given to the Egyptians so that they could give eternal life to all their dead. The spells and rituals cast by Isis, plus many others given to the people by the gods over the centuries, were collected into The Book of Going Forth by Day, colloquially known as The Book of the Dead.

In the underworld, Osiris sits on a great throne, where he is praised by the souls of the just. All those who pass the tests of the underworld become worthy to enter The Blessed Land, that part of the underworld that is like the land of the living, but without sorrow or pain. In some texts, in addition to the Judging of the Heart, Osiris passes final judgment over the dead, acting in this capacity as an Egyptian version of Radamanthus.

Isis as the goddess of fertility her status as the Mother is propagated by the services provided her by Osiris. Once again linking his image with that of the Horned One. He is also often "merged" with the Greek God Dionysus, some believing that the two of them were in fact the same God, perceived through slightly different cultural lenses. Then again, it may also be that they are only Gods who share similar roles, myths, histories, and spheres of influence while remaining completely separate, autonomous individuals. And then again, it may be that their similarities are highly inflated, perceived only because the reader desires to see a connection between them, and conveniently disregards those areas where they differ.

There is also an interesting parallel between Osiris, a fertility/agriculture god, and the Greek Persephone, an agriculture goddess. Both end up in the underworld through treachery and both are kept there by "legal loopholes" in the laws of the gods. Persephone remains in the underworld for half a year because she tasted the food of the dead. Osiris remains in the underworld because Ma'at dictates that the dead, even dead gods, may not return to the land of the living.