Apep was the enemy of Ra, the supreme God of the Egyptian pantheon. He was a terrifying serpent who symbolised chaos and destruction. Each day, as the sun God, Ra, crossed the sky in his boat, Apep would viciously attack the vessel. During a total eclipse, he was believed to have swallowed it whole.

Despite his fierceness, Apep never gained total victory over his enemy, although at the same time, he himself was never believed to have been completely conquered. The reddening of the sky at dusk was said to demonstrate that the serpent had been overcome by the sun's strength.