Nyx is a woman in her early 40's, but uses dark magic to make herself look younger. Her graying hair is the only sign of her age. She is dressed in a long black robe and carries a staff carved from a dead tree. She has rather pointy features, including her fingernails.
Nyx is an evil Goddess who shows no affection for anyone besides Perseus, and what affection she does have, she does not express often. Unlike Hades in Uprising, she prefers to stay out of Pit's business and does not comment much. When she does speak, however, she does so with much contempt for the angels and other Gods. Even Hades agreed that she is out of control and must be stopped.