In the most famous story regarding them they are appeased when given the name "kindly ones" after they pursue Orestes to Athens.  
In the Iliad they strike dumb Xanthus, Achilles' talking horse, when he prophesizes his master's death.  According to Hesiod they were one of the many entities formed when the blood of the castrated Ouranos fell upon the Earth, while Aeschylus asserts that they are the offspring of Night.  In the most famous story regarding them they are appeased when given the name "kindly ones" after they pursue Orestes to Athens.  Although their number is often indeterminate, many ancient writers numbered them at three: Alecto, Megaera, and Tisiphone.  FTP, identify these appalling and avenging spirits of Greek myth.
In the Iliad they strike dumb Xanthus, Achilles' talking horse, when he prophesizes his master's death.  
Erinyes, or Furies or Eumenides