Nyx is the goddess of night and darkness. She isn't a major, but plays a big part. She watches over the shadows of the night and tries her best to keep the night safe, though she has terrible persona and is quite feared a lot around Mount Olympus. Therefore for all the hate she gets, she is not a major resident of Mount Olympus either.
Nyx is a major premival god. She is one of the only female major premival gods, since most of them are male Titans.
Nyx isn't normally seen or heard from because she can just be the shadow or the moon, but she is very quiet and timid, with a little twist of hate. Her daughter is the goddess Hemera, goddess of daylight. Nyx hates Hemera because of her daughters positive attitude to things. But her other daughter, Achlys, is making her proud with her hateful and demeaning attitude, clawing her face as she is the goddess of torture. She has other daughters like Eris, Arai, Geras and demons. Hypnos, the god of sleep is her son.
She is most likely friends with Selene, goddess of the moon, but Nyx is more hateful and evil than Selene.
Nyx's gallery can be found here.
Her Roman name is Nox.
Nyx's official Greek name is Νυξ.