The Furies,
The Furies also called Erinnyes were some seriously fearsome creatures. They were conceived when Uranus' spilled blood hit Gaia's body, and were therefore older than any of the Olympian Gods. "These Erinnyes are crones with snakes for hair, dogs' heads, coal-black bodies, bats' wings, and bloodshot eyes. In their hands they carry brass-studded scourges and their victims die in torment." It isn't a great idea to mention their names in conversation, so instead you should call them the Eumenides, or the Kindly Ones. There are three:
* Tisiphone, the Avenger
* Megara, the Jealous
* Alecto, the Unresting
Their purpose was to torment sinners, which they did on Earth as well is in Tartarus. The sight of one could cause insanity, and they often drove offenders to suicide. Originally they punished only offenders of patricide, matricide, or breakers of oaths, but after a while they punished any sins. They lived in Erebus (Darkness) but traveled the Earth constantly in search of transgressors. The Furies get special press in the play the Eumenides from the Oresteia of Aeschylus. Sadly, the thing ends with the loss of a lot of their power. During their day they received plenty of respect, and that included sacrifices of honey and water. Narcissus flowers and doves seem randomly sacred to them. If you like them, you should check out their buddies like the Keres, Dike, Eris, the Harpies, the Fates, Nemesis, and Poene.