The Erinyes (/ɪˈrɪni.iːz/ ih-RI-nee-eez; Ancient Greek: Ἐρινύες, sg. Ἐρινύς Erinys), also known as the Eumenides (Εὐμενίδες, the "Gracious ones"), are chthonic goddesses of vengeance in ancient Greek religion and mythology. A formulaic oath in the Iliad invokes them as "the Erinyes, that under earth take vengeance on men, whosoever hath sworn a false oath". Walter Burkert suggests that they are "an embodiment of the act of self-cursing contained in the oath". Their Roman counterparts are the Furies, also known as the Dirae. The Roman writer Maurus Servius Honoratus (c. 400 AD) wrote that they are called "Eumenides" in hell, "Furiae" on Earth, and "Dirae" in heaven. Erinyes are akin to some other Greek deities, called Poenai.

According to Hesiod's Theogony, when the Titan Cronus castrated his father, Uranus, and threw his genitalia into the sea, the Erinyes (along with the Giants and the Meliae) emerged from the drops of blood which fell on the Earth (Gaia), while Aphrodite was born from the crests of sea foam. Apollodorus also reports this lineage. According to variant accounts, they are the daughters of Nyx ('Night'), while in Virgil's Aeneid, they are daughters of Pluto and Nox (the Roman name for Nyx). In some accounts, they were the daughters of Eurynome (a name for Earth) and Cronus, or of Earth and Phorcys (i.e., the sea). In Orphic literature, they are the daughters of Hades and Persephone.

Their number is usually left indeterminate. Virgil, probably working from an Alexandrian source, recognized three: Alecto or Alekto ("endless anger"), Megaera ("jealous rage"), and Tisiphone or Tilphousia ("vengeful destruction"), all of whom appear in the Aeneid. Dante Alighieri followed Virgil in depicting the same three-character triptych of Erinyes; in Canto IX of the Inferno, they confront the poets at the gates of the city of Dis. Whilst the Erinyes were usually described as three maiden goddesses, "Telphousia" (a name for Erinys) was a byname for the wrathful goddess Demeter, who was worshipped under the title of Erinys in the Arcadian town of Thelpusa.

The word Erinyes is of uncertain etymology; connections with the verb ὀρίνειν orinein, "to raise, stir, excite", and the noun ἔρις eris, "strife" have been suggested; Robert Beekes suggests that the word probably has a Pre-Greek origin. The word Erinys in the singular and as a theonym is first attested in Mycenaean Greek, written in Linear B, in the following forms: 𐀁𐀪𐀝, e-ri-nu, and 𐀁𐀪𐀝𐀸, e-ri-nu-we. These words are found on the KN Fp 1, KN V 52, and KN Fh 390 tablets.

The Erinyes live in Erebus and are more ancient than any of the Olympian deities. Their task is to hear complaints brought by mortals against the insolence of the young to the aged, of children to parents, of hosts to guests, and of householders or city councils to suppliants—and to punish such crimes by hounding culprits relentlessly. The appearance of the Erinyes differs between sources, though they are frequently described as wearing black. In Aesychlus' Eumenides, the Priestess of Pythian Apollo compares their monstrosity to that of the gorgon and harpies, but adds that they are wingless, with hatred dripping from their eyes. Euripides, on the other hand, gives them wings, as does Virgil. They are often envisaged as having snakes in their hair.

The Erinyes are commonly associated with night and darkness. With varying accounts claiming that they are the daughters of Nyx, the goddess of night, they're also associated with darkness in the works of Aeschylus and Euripides in both their physical appearance and the time of day that they manifest.

Description of Tisiphone in Statius' Thebaid:

So prayed he, and the cruel goddess turned her grim visage to hearken. By chance she sat beside dismal Cocytus, and had loosed the snakes from her head and suffered them to lap the sulphurous waters. Straightway, faster than fire of Jove or falling stars she leapt up from the gloomy bank: the crowd of phantoms gives way before her, fearing to meet their queen; then, journeying through the shadows and the fields dark with trooping ghosts, she hastens to the gate of Taenarus, whose threshold none may cross and again return. Day felt her presence, Night interposed her pitchy cloud and startled his shining steeds; far off towering Atlas shuddered and shifted the weight of heaven upon his trembling shoulders. Forthwith rising aloft from Malea’s vale she hies her on the well-known way to Thebes: for on no errand is she swifter to go and to return, not kindred Tartarus itself pleases her so well. A hundred horned snakes erect shaded her face, the thronging terror of her awful head; deep within her sunken eyes there glows a light of iron hue, as when Atracian spells make travailing Phoebe redden through the clouds; suffused with venom, her skin distends and swells with corruption; a fiery vapour issues from her evil mouth, bringing upon mankind thirst unquenchable and sickness and famine and universal death. From her shoulders falls a stark and grisly robe, whose dark fastenings meet upon her breast: Atropos and Proserpine herself fashion her this garb anew. Then both her hands are shaken in wrath, the one gleaming with a funeral torch, the other lashing the air with a live water-snake.