Lamia- often associated with Medusa or Lilith, she was a snake goddess from Crete who ruled the Underworld. She was changed by patriarchal Greeks into a nightmare goddess who stole children and sucked their blood.
Nyx, Greek Goddess of the night. Nyx was depicted as riding in a chariot, trailing stars and bringing the night, and accompanied by Her sons Hypnos and Thanatos. She could be helpful or harmful to mankind, bringing either sleep or death.