Superman: New Krypton
It is revealed in the DC comics event New Krypton that according to the Kryptonian mythology, Rao is the first being to be born out of the void before the universe. Feeling lonely, he sought to bring order to the chaos from which he was born, and thus created the universe. After countless eons of ordering the cosmos, Rao created Krypton, a planet meant to be a jewel in his creation. Rao then created all the other Kryptonian gods from his own essence, and these "godlings" called him "Father Rao". Rao, in the time just before and after the destruction of Krypton, is thought of by the people of Krypton like the God in Abrahamic Religions is on Earth. He is all knowing, all powerful and eternal. He is served by his minor gods, who could be better understood as his angels. Each minor god is worshiped by a guild or caste on Krypton while all people worshiped Rao.
The people of Krypton call their powers under a yellow sun the power of Rao. The high priest of Krypton is said to be the Voice of Rao and only speaks to voice Rao's judgement. Rao works through avatars. The Nightwing and the Flamebird are two mythological dragon/phoenix creatures who serve Rao; the Nightwing of shadow and the Flamebird of Fire. Each generation, Nightwing and Flamebird are reborn in two individuals who are blessed with a great love for each other that is doomed to end tragically in death. According to the comics just before the destruction of Krypton the Nightwing and Flamebird of that generation tried to avoid each other, believing themselves to be crazy to feel the influence of the myths.
In the New Krypton story line, the Phantom Zone prisoner Jax-Ur becomes possessed by a minor Kryptonian god obsessed with ending the world and making a new one. Jax-Ur takes part of Nightwing and Flamebird to make a fake body of the God Rao that he uses to absorb more energy to end the world and make a new one. As the military around the world only help to make the fake god more powerful, Nightwing, Flamebird, and the JSA try to stop Rao but do little until Wonder Woman, armed with an axe blessed by her Greek Gods, is able to hurt Rao. In the end, Nightwing opens a portal to the Phantom zone sending Jax-Ur and his fake Rao in to the Phantom Zone.
The fake body remains are used by Lex Luthor with a time machine and a ballistic missile to turn Earth's sun red during the "War of the Supermen" storyline to destroy most of the Kryptonians.
Read more about this topic: Rao (comics)