Nyx is the primordial Greek goddess (or personification) of the night. A shadowy figure, Nyx stood at or near the beginning of creation and mothered other personified deities such as Hypnos (Sleep) and Thanatos (Death), with Erebus (Darkness). Her appearances are sparse in surviving mythology, but reveal her as a figure of such exceptional power and beauty that she is feared by Zeus himself.
She is depicted as a goddess draped in long flowing black robes that are coated with the void of space and glimmering distant stars.
Nyx, alongside her Primordial siblings, is born of Chaos. With Erebus (Darkness), Nyx gives birth to Aether (Brightness) and Hemera (Day). Later, on her own, Nyx gives birth to Moros (Doom, Destiny), Ker (Destruction, Death), Thanatos (Death), Hypnos (Sleep), the Oneiroi (Dreams), Momus (Blame), Oizys (Pain, Distress), the Hesperides, the Moirai (Fates), the Keres, Nemesis (Indignation, Retribution), Apate (Deceit), Philotes (Friendship), Geras (Old Age), and Eris (Strife).
One account that details Zeus' fear of Nyx is when Hypnos, the god of sleep, reminds Hera of an old favor after she asks him to put Zeus to sleep. He had once before put Zeus to sleep at the bidding of Hera, allowing her to cause Heracles, who was returning by sea from Laomedon's Troy, great misfortune. Zeus was furious and would have smitten Hypnos into the sea if he had not fled to Nyx, his mother, in fear. In fact, the king of the gods was fearful to the point where he held his fury at bay and in this way Hypnos escaped the wrath of Zeus by appealing to his powerful mother. He disturbed Zeus only a few times after that always fearing Zeus and running back to his mother, Nyx, who would have confronted Zeus with a maternal fury.