Erinyes
The Greek goddesses of retribution. There were three of them, with hideous features, snakes for hair, and eyes which wept blood. They sprang from the blood of Uranus when his son Chronos struck him down. Their purpose was to punish those who broke the laws of nature, such as killing a family member. The Romans called them the Furies.
When Hera endowed a horse with the power of speech, the Erinyes struck it dumb because it was not natural for a horse to talk.