The Furies were chthonic (underworld) goddesses of vengeance. They persecuted oath-breakers, patricides, matricides, and other violators of divine law. Their relentless pursuit manifested in several ways, the most severe being a tormenting, self-destructive madness. The latter might have personified the guilt of the criminal. They were depicted in several ways in art and poetry. The most notable depictions feature them with snakes for hair and blood dripping from their eyes.
There were a number of contradictory accounts of their origin. The most notable feature them either as daughters of the goddess Nox, or born from the blood of the primordial god Uranus which fertilized the Earth goddess, Gaea. Said blood was spilt when Uranus was castrated by his own son Cronos. The first act of patricide or filial disloyalty gave birth to the spirits of vengeance.
The Three Furies
The Furies are most often depicted in popular media (as well as ancient artwork) as three anonymous, largely identical beings simply known as "The Furies." The three Furies, Alecto, Megaera, and Tisiphone are therefore difficult to distinguish from each other. Certain interpretations of Furies have even depicted them as an entire race of mythical beings that seek vengeance, rather than the three specific goddesses that they are known as.