Aornis

Aornis may refer to:
 * Aornis Hades, the Thursday Next series character, or her namesake, a fictional tributary of the river Styx.

See also:
 * Aornos, the site of the battle fought by Alexander the Great's forces
 * Avernus, a volcanic crater in Italy called Aornos by the Greeks, thought to be the entrance to the Underworld.