Nyx was the goddess of the night, one of the ancient Protogenoi. In the cosmogony of Hesiod she was born of Khaos, and breeding with Erebos produced Aither and Hemera, first components of the primeval universe. Alone, she spawned a brood of dark spirits, including the three Fates, Sleep, Death, Strife and Pain.
Nyx was a primeval goddess usually represented as simply the substance of night: a veil of dark veil of mist drawn forth from the underworld which blotted out the light of Aither (shining upper atmosphere). Her opposite number was Hemera, who scattered the mists of night, or Eos, the goddess of the dawn.
In ancient art Nyx was portrayed as a either a winged goddess or charioteer, sometimes crowned with an aureole of dark mist.source: www.theoi.com
image: william adolphe bouguereau – la nuit