In Roman mythology, the Furies also known as the Dirae (The Terrible) (Erinyes or Erinnyes (The Angry Ones) in Greek mythology) are three sisters: Alecto (The Unceasing or The Endless who was their leader), Megaera (The Grudging or The Envious Rager) and Tisiphone (The Avenging or The Retaliator). There are two accounts of their creation. One account has it that they came into being when the blood produced by Cronus castrating his father Uranus splashed upon the Earth, Gæa. The other account has it that they were mothered by Gæa with air and bad human emotions and deeds such as murder, perjury, disrespect, ingratitude, harshness, and violation of filial piety and the laws of hospitality.

They are the goddesses of revenge, sometimes called the daughters of the Night or Those Who Walk in Darkness. They haunt criminals, especially those who kill or commit wrongs against blood relatives, regardless of motivation, until they go insane and die. The Furies are untiring and persistent in their pursuit. They are impartial and indifferent, merely carrying out their duty. They continue to torment wrongdoers even after death, until the criminal shows remorse. Then, they become the Eumenides (The Kindly Ones, Protectors of the Suppliant, The Well-Disposed Ones) or the Semnai (The Venerable Ones). They were often referred to as Eumenides, as calling them Furies was concidered bad luck. The Furies have also been referred to as the Potniae (The Awful Ones), the Maniae (The Madnesses), and the Praxidikae (The Vengeful Ones). Vergil (or Virgil) placed them in the Underworld, tormenting sinners under the command of Pluto, but Greek poets often presented them as pursuing criminals on Earth, under the command of Zeus. However, the Furies are also said to steer the great goddess Ananke (Necessity), who is more powerful than even Zeus, in that he can not escape what is necessary.

While they are sometimes presented as being very fair, artists often depicted them as crones with fiery eyes, bats' wings, dogs' heads and snake hair, often brandishing torches and metal-studded whips. Sometimes they were dressed as hunters. Weeping tears of blood and hissing with hair of vipers, they would descend like a storm. Ancient authors described them as stinking of rotting mortal blood (which they also spat out) and barking like bitches. They could not die as long as sin existed in the world. Tisiphone guards the entrance to Tartarus, wrapped in a bloodstained robe. Alecto is a maker of grief. She revels in war and quarrels. Little is said about Megaera.