In Iliad 14 there is a moment that changes the scale of everything around it. Hypnos, the god of sleep, is being asked by Hera to put Zeus to sleep, and refuses at first — he did it once before, and when Zeus woke he turned the household upside down hunting the culprit, and would have flung him into the sea if Hypnos had not run to Nyx, "subduer of gods and men". At that point, Homer says, the king of the gods stopped, because he was not willing to displease Night.
That is the only being in Homer that Zeus is afraid of. She has almost no cult, very few images and no adventures, and the king of the gods will not cross her.
First or second
Hesiod's Theogony puts Chaos first, then Earth, Tartarus and Eros; from Chaos come Erebus and Night, and from Night — mating with Erebus — come Aether and Day. Then, without a partner, she produces a catalogue of powers that reads like a list of everything wrong with existence: Doom, Fate, Death, Sleep, the tribe of Dreams, Blame, Distress, the Hesperides, the Moirai and the Keres, Nemesis, Deceit, Old Age, and Strife. Strife then produces Toil, Forgetfulness, Famine, Sorrow, Battles, Murders, Lies, Lawlessness and Ruin.
The Orphic cosmogonies reverse the order and make Night the beginning. In the version summarised by later Neoplatonists, Night is the first principle, sitting in a cave, giving oracles to Zeus — who, in one Orphic theogony, consults his ancestress Night about how to organise the cosmos and is instructed by her. A universe founded on Night rather than on a gap is a genuinely different theology, and Aristophanes' Birds parodies a version of it with the wind-egg laid in the boundless bosom of Erebus.
Which came first, Chaos or Night, was therefore a live question between rival Greek cosmologies, not a detail. It is one of the clearest cases where two ancient systems answer the same question incompatibly and both were current.
What her children have in common
Look at the list and the logic is visible: everything born of Night is something that happens to you without your consent and cannot be argued with. Sleep and Death are the plainest, and the Greeks made them twin brothers deliberately. The Keres are violent deaths on the battlefield; the Moirai are the allotment you were born with; Nemesis is retribution that arrives whether or not anyone brings a case; Geras is old age. There are no gods of choice in her family.
The Hesperides are the odd ones out — nymphs of the evening garden at the world's western edge with the golden apples — and they belong there simply because evening is where the sun goes.
Where she appears
She has essentially no temples. Pausanias records an oracle of Night at Megara, which is nearly the whole of her cult record, and there are scattered references to black offerings. But she is present constantly in poetry and philosophy, and she is present in art at one remarkable place: the Pergamon Altar frieze, where a figure identified as Night hurls a snake-entwined vessel into the Gigantomachy.
Her most quoted single line comes from a hymn: she is called "mother of gods and men". Orphic Hymn 3 addresses her as the origin of all things, "Kypris" among the blessed, bringer of sleep, friend of the revel, and asks her to come benevolently and dispel fears that shine in the dark.
Nox, and the long afterlife
The Roman Nox is little more than a translation, though Virgil and Statius use her effectively; Statius' Thebaid has a striking invocation. Roman art occasionally shows her as a woman with a dark veil arched over her head, sometimes in a chariot with stars, sometimes scattering poppies — the "night sky as a veil" motif that runs unbroken into Renaissance and Baroque ceiling painting.
Modern reception has been unusually good to her. Because she is powerful, ancient, largely undescribed and clearly frightening, she is exactly the kind of figure fantasy wants: she recurs across novels, games and comics as a primordial darkness — sometimes as a villain, sometimes as an implacable neutral force. The name is also used for spacecraft and telescopes and, curiously, for the moth family Noctuidae by an unrelated route. The Orphic version — a goddess whom Zeus himself asks for advice — is the one most modern writers reach for, usually without knowing which tradition it comes from.
Her children, the Orphics, and the one thing Zeus will not risk
Is she the same as Chaos?
No, though modern retellings often merge them. Hesiod's Chaos is a chasma, a gap or yawning void, and is not personified as a character with plans; Night is a mother with a family and a cave and a house at the edge of the world, where she and Day pass each other on the threshold, one going out as the other comes in. That image, in Theogony 748–757, is the most concrete description she gets and one of the best pieces of visual writing in early Greek poetry.
Which of her children matter most?
Thanatos and Hypnos are the most depicted in art, particularly on funerary monuments and on the famous vase showing them carrying the body of Sarpedon. The Moirai are the most theologically consequential, since their power over fate raises the question of whether Zeus is sovereign. Nemesis acquired the largest independent cult, at Rhamnous in Attica. Charon is assigned to her by later mythographers rather than by Hesiod.
Does she appear in the Orphic mysteries?
She is central to the Orphic theogonies as they are reconstructed from quotations, papyrus fragments and Neoplatonic summaries — particularly the Derveni papyrus, a carbonised roll found in a Macedonian tomb in 1962, which quotes and interprets an Orphic poem and mentions Night's oracular instruction of Zeus. That document is the oldest surviving European manuscript and it is, in part, about her.
Why does Zeus fear her and not the Fates?
He fears both, in different registers. The Iliad passage about Night is about personal power and reluctance to offend. The question of whether Zeus can override the Moirai is separate and is raised explicitly when he considers saving his son Sarpedon and Hera talks him out of it, warning that the other gods would follow suit. Greek theology never resolved whether fate constrains Zeus or is administered by him, and the two passages sit a few books apart without being reconciled.