Nox's true origins is unknown, but she predates the Olympians.
In the 1930s she allied herself with the General in an effort to gain power, leading him to the Amulet of Achilles, and forcing him to make human sacrifices to sustain his own life, and occasionally enabling her to enter the mortal realm by inhabiting their corpses. Following the General's sacrifice of the town of Dark Hollow, West Virginia she was finally able to fully appear on Earth, helping him carry out their plans.
Nox claimed responsibility for introducing Psycho-Man to the study of fear. She also guided Thog in his scheme regarding Nightmare boxes.
In Greek mythology, Nyx is a literal personification of the night.
Hesiod's Theogony includes a genealogy of the gods. Listed children of Nyx include other personifications of concepts, such as Aether (Brightness), Apate (Deceit), Eris (Strife), Geras (Old Age), , Hemera (Day), the Hesperides (Evening, Sunset), Hypnos (Sleep), Ker (Fate, Destruction, Death), the Keres (female Death spirits), the Moirai (Fates), Momus (Blame), Moros (Doom, Destiny), Nemesis (Indignation, Retribution, heavenly punishment for excessive hubris), Oizys (Woe, Pain, Distress), the Oneiroi (Dreams), Philotes (Friendship, Love), and Thanatos (Death).
Nyx is a minor character in the Illiad by Homer. It is mentioned that Hypnos, God of Speep put Zeus to sleep to allow Hera free hand in one of her plots. Zeus is furious when he finds out and wants to attack him. Hypnos then goes to his mother Nyx for protection. Zeus has to stop as he is too intimidated by the goddess to risk angering her.