Hecate was a popular and ubiquitous goddess from the time of Hesiod until late antiquity. Unknown in Homer and harmless in Hesiod, she emerges by the 5th cent. as a sinister divine figure associated with magic and witchcraft, lunar lore and creatures of the night, dog sacrifices and illuminated cakes, as well as doorways and crossroads. Her name is the feminine equivalent of Hekatos, an obscure epithet of Apollo (Chantraine, Dictionnaire étymologique de la langue grecque (Paris 1968–80) 1. 328 on ἔκατος‎, ἑκατηβόλος‎), but the Greek etymology is no guarantee that her name or cult originated in Greece. Possibly of Carian origin (see caria), and certainly outlandish in her infernal aspects, she is more at home on the fringes than in the centre of Greek polytheism. Intrinsically ambivalent and polymorphous, she straddles conventional boundaries and eludes definition.

In Hesiod's Theogony she is the granddaughter of the Titans Phoebe and Coeus, daughter of Perses and Asteria, and first cousin of Apollo and Artemis (for other genealogies see schol. Ap. Rhod. Argon. 3. 467). In a remarkable digression (Theog. 411–52), the authenticity of which has been unduly doubted, Hecate is praised as a powerful goddess who ‘has a share’ of earth, sea, and sky—but not the Underworld—and who gives protection to warriors, athletes, hunters, herders, and fishermen. As with all gods, she may choose to withhold her gifts. But, because her functions overlap with those of other divinities, she lacks individuating features. Furthermore, the Hesiodic Hecate contrasts sharply with the goddess's later manifestations, which tend to be much more menacing. Where and how this differentiation happened remains uncertain.

Throughout her long history, Hecate received public as well as private cult, the latter often taking forms that were anything but normal. She was worshipped in liminal places, and sacrifices to her were as anomalous as the goddess herself. The earliest archaeological evidence is a dedication to Hecate on a circular altar in the precinct of Apollo Delphinios at Miletus (A. Rehm, Milet. 1. 3 (Berlin, 1914), no. 129, before 500 bce); she had her own shrine ‘outside the gates’—as opposed to the Coan cult (see cos) of Hecate ‘in the city’ (LSCG 169 A 5)—where she received libations of unmixed wine (LSAM 50. 25–9, 450 bce). In Athens Hermes Propylaios and Hecate Epipyrgidia (‘On the Ramparts’) guarded the entrance to the Acropolis (Paus. 1. 22. 8, 2. 30. 2). Similarly, altars and cult images of the trimorphic Hecate (hekataia) stood in front of private homes (Aesch. fr. 388 Radt, Ar. Vesp. 804) and especially at forks in the road (Apollodorus of Athens, FGrH 244 F 110), after which she was named τριοδῖτις‎ and Trivia.

The documentation for the Hecate cult in Classical Athens is particularly rich and varied. Her favourite food offerings consisted of a scavenging fish (see fish, sacred) tabooed in other cults—the red mullet (τρίγλα‎, Apollodorus 244 F 109; Antiphanes fr. 69. 14 f. K–A)—of sacrificial cakes decorated with lit miniature torches (Soph. fr. 734 Radt; Diphilus fr. 27 K–A; LIMC ‘Hekate’, no. 47), and, most notoriously, of puppies (Ar. frs. 209, 608 K-A). The illuminated cakes were offered at the time of the full moon (Philochorus, FGrH 328 F 86). So-called ‘suppers of Hecate’ (Ἑκαταῖα‎ sc. δεῖπνα‎)—consisting of various breadstuffs, eggs, cheese, and dog-meat—were put out for her at the crossroads each month to mark the rising of the new moon (Ari.Plut. 594 ff. with schol., fr. 209 K–A). On an Attic lecythus, a woman deposits a puppy and a basket with sacrificial cakes in front of burning torches (Beazley, ARV² 1204. 2). Attested for Athens, Colophon, Samothrace, and Thrace, dog sacrifices to Hecate were alimentary as well as cathartic (Sophron fr. 4.7 K-A; Plut. Quaest. Rom. 280c, 290d). During Hellenistic and Roman times, she was worshipped as the regional mother-goddess at her main Carian sanctuary at Lagina near Stratonicea. There, the ritual carrying of a sacred key (κλειδαγωγία‎) was part of her cult, the clergy of which included a priest and priestess as well as eunuchs. On the temple frieze, Hecate carries to Cronus the stone that represents the newborn Zeus; in another scene, she participates in the Gigantomachy (LIMC nos. 98–100; see giants). No dogs were sacrificed in the Lagina cult, but the puppy sacrifices, prominent in Hittite and Carian purification rituals, point to an early Anatolian connection. See anatolian deities.

Hecate was identified with other divine figures such as Ereschigal, the Babylonian goddess of the Underworld (PGMlxx); the Thessalian Enodia (Soph. fr. 535. 2 Radt; Eur. Hel. 569 f.) and Brimo (Ap. Rhod. Argon. 3. 861 f., 1211; LIMC nos. 303, 305); the Sicilian Angelos (schol. Theocr. 2. 11/12b; cf. R. Arena, Iscrizioni greche arcaiche di Sicilia e Magna Grecia 1 (1989), no. 38 = L. Dubois, Inscriptions grecques dialectales de Sicilie (1989), no. 55, c.450 bce); Persephone (Soph. Ant. 1199 f., Eur. Ion 1048 f.); Iphigenia (Stesichorus fr. 215 Davies, PMGF; Paus. 1. 43. 1, cf. Hesiod fr. 23a. 26 M–W); and especially Artemis (IG 12. 8. 359, Thasos, c.450 bce; IG 4². 499, Epidaurus, imperial period). In Athens, too, she was worshipped as Artemis Hecate (IG 1³. 383. 125–7, 429/8 bce) and as Kalliste, another of Artemis' cult titles (Hesychius κ‎ 489; cf. IG 2². 4665–8). Sacrifices to Artemis Hecate and to Kourotrophos were performed in Hecate's shrine at Erchia in Attica (LSCG 18 B 6–13, 375/50 bce). Hecate was also associated with various male gods, including Apollo Delphinios, Asclepius, Hermes, Pan, Zeus Meilichios, and Zeus Panamaros.

Like all chthonian divinities, Hecate was perceived as simultaneously terrible and benign. Her ‘good’ side is addressed by her Hesiodic epithet ‘nurturer of the young’ (Hes. Theog. 450 κουροτρόφος‎, echoed in later sources). In Aeschylus, the title ‘Hekata’ refers to Artemis in her association with childbirth (H. F. Johansen and E. W. Whittle, Aeschylus: The Suppliants (1980) on Supplices 676) and young animals (Aga. 140 West). The Hecate seen in Eleusinian myth and cult is propitious and caring. She assists Demeter in her search for Persephone (Kore), and after the reunion of mother and daughter becomes Kore's ‘minister and attendant’ (Richardson on Hym. Hom. Cer. 24 f. and 440). Attic vase-painters included Hecate in their depictions of the return of Kore and the mission of Triptolemus (LIMC nos. 10–23); in the Attic deme of Paiania, Hecate's cult and priestess were attached to the local Eleusinion (IG 1³. 250 = LSS 18, 450/30 bce). In later versions of the myth, Hecate is another daughter of Demeter and retrieves Persephone from the Underworld (Callim. fr. 466 Pf., Orph. fr. 400 Bernabé). Mystery cults (see mysteries) of Hecate also existed, as on Aegina and Samothrace; a woman initiate claims on her tombstone to have been immortalized in death as the ‘goddess Hecate’ (GVI 438a, Thrace, imperial period).

Although Hecate lacked a mythology of her own, her nocturnal apparitions, packs of barking hell-hounds, and hosts of ghost-like revenants occupied a special place in the Greek religious imagination. As ‘the one of the roadways’ (ἐνοδία‎), she protected the crossroads as well as the graves by the roadside. She also guarded the gates to Hades. According to one of the hymns to Selene-Hecate embedded in the Paris magical papyrus, Hecate keeps the keys that ‘open the bars of Cerberus’ and wears ‘the bronze sandal of her who holds Tartarus’ (PGMiv 2291–5, 2334 f.; cf. Suppl. Mag. 49. 57–61). A permanent fixture of the Greek and Roman Underworld, she gives Virgil's Sibyl, a priestess of Apollo and Hecate, a guided tour of Tartarus (Aen. 6. 35, 564 f.). Because of her association with the chthonian realm and the ghosts of the dead, Hecate looms large in ancient magic. Sorceresses of all periods and every provenance, such as Medea, Simaetha, and Canidia, invoke her name as one who makes powerful spells more potent (Soph. frs. 534–5 Radt; Eur.Med. 397; Ap. Rhod. Argon. 3. 1035 ff.; Theoc. Id. 2. 12–16; Hor. Sat. 1. 8. 33). On curse tablets (see curses) dating from the Classical to the imperial period, Hecate is conjured in conjunction with Hermes Chthonios, Gē (see gaia) Chthonia, Persephone, or Pluton (see hades) (Def. tab. A. Audollent, nos. 38, 41, Wünsch, nos. 104–7). In a specimen from Hellenistic Athens, Hecate Chthonia is invoked ‘along with the maddening Erinyes’ (no. 108b 2 Wünsch = Gager no. 69). Hecate is equally prominent in the magical papyri, where she is often identified with Baubo, Brimo, Persephone/Kore and Selene (Fauth 2006, 27–76). In the theurgy of the Chaldaean Oracles adopted by the Neoplatonists, Hecate, though still linked to demons, has become an epiphanic celestial deity (see epiphany) and cosmological principle—the Cosmic soul—accessible through ritual as well as contemplation.

Representations of Hecate in art fall into two broad categories: her images are either single-faced or three-faced. The earliest example of the former type may be an inscribed terracotta figurine of a woman seated on a throne, dedicated by ‘Aigon to Hecate’ (Athens, late 6th cent. bce; IG 1². 836; LIMC no. 105). After c.430 bce, the goddess of the crossroads is often represented as a standing female figure with three faces or bodies, each corresponding to one of the crossing roads. The trimorphous Hecate is said to be the creation of Alcamenes (LIMC no. 112). She is often shown wearing the polos (divine head-dress) and holding torches in her hands (Hym. Hom. Cer. 52; LIMC nos. 1–94), and occasionally with a phiale, a sword, snakes, boughs, flowers, or a pomegranate. Central to her cult, the three-faced image of Hecate is depicted on two Attic vases from the Classical period (LIMC nos. 48, 206). On the Altar of Zeus at Pergamum, Hecate and her dog attack a serpentine giant; her single body supports three heads and three pairs of arms (LIMC no. 191). Exceptionally, on a calyx crater with the death of Actaeon, a winged Hecate urges on his maddened dogs while Artemis looks on (LIMC no. 96). On an equally unique vase, Hecate has man-eating dogs for feet and is accompanied by three Erinyes (LIMC no. 95).

Greek wordsmiths went to great lengths in their efforts to verbalize the triple aspects of the trimorphic goddess. In one of the comedies of Chariclides, she is humorously invoked as ‘Lady Hecate of the triple roads, of the triple form, of the triple face, enchanted by triple-fish [mullets]’ (fr. 1 K–A δέσποιν᾽ Ἑκάτη τριοδῖτι‎, τρίμορφε‎, τριπρόσωπε τρίγλαις κηλευμένη‎). A curse tablet from the imperial period addresses her similarly as ‘Lady Hecate of the heavens, Hecate of the Underworld, Hecate of the three roads, Hecate of the triple face, Hecate of the single face’ (SEG 30. 326 = Gager no. 84; cf. iv 2525–30, 2820–6). Playing with sacred numbers added to her mystery.