Erebus

Pegasus a winged divine stallion. Pegasus is usually represented as pure white in color. in the myth Pegasus is a son of the Olympian god poseidon It was sired by the Gorgon Medusa.

Reference
Pegasus are mentioned in Secrets of the Ancient World was the guide used by game masters of the Hercules & Xena Roleplaying Game by West End Games.