Akhlys

"The Death Mist is not for helping! It shrouds mortals in misery as their souls pass into the Underworld. It is the very breath of Tartarus, of death, of despair!"

- Akhlys to Iapetus

Akhlys (also known as Achlys) is the Greek goddess of misery and poison and is the keeper of the Death Mist. She lives in Tartarus.

History
Little is known about Akhlys except that she may have been created before Chaos.

The House of Hades
Percy Jackson and Annabeth Chase meet Akhlys to so they can hide themselves in the Death Mist. She betrays them however, and being also goddess of poison chucks poison at the pair. Percy uses his powers over water to will the poison back to her, which causes her to flee from them. It is during this that a darker force in Percy's persona reveals itself.

Appearance
Akhyls looks like a victim of famine. She has large amounts of dust covering her thin body. She has a drippy nose,  bloody red clawed cheeks, sunken eyes, and stringy gray hair that is matted to her head.

Akhlys appeared on the shield of Hercules as pale, emaciated, and weeping, with chattering teeth, swollen knees, long nails on her fingers, bloody cheeks, and her shoulders thickly covered with dust.

Trivia

 * It is said that her mother is the eternal night and that she existed even before Chaos. While Nyx is the goddess of night, it is uncertain if Akhlys is referring to Nyx or possibly an even older entity, as Nyx came from Chaos.
 * Although, she is thought to be created before Chaos, in The House of Hades she states that she is his daughter. This could mean that Nyx is her mother.