Hecate (Hekate) was an underworld/chthonic, moon, or crossroads goddess in Greek mythology. Her parents are variously given as Perses and Asterie or Asterie and Zeus, among others. Hesiod shows Hecate as a helper of men, honored by Zeus and the Titans, but not an underworld or lunar goddess. In the Homeric Hymn to Demeter, it is Hecate who tells Demeter where her daughter Persephone has gone. Hecate becomes an attendant of Persephone, queen of the Underworld. In the Megalai Ehoiai, Hecate is the mother of Scylla, the sea monster of the Odyssey [see Odyssey Book XII]. Pindar appears to link Hecate with the moon.
Hecate is equated with Crataiis (mother of Scylla); with Persephone, in Callimachus; with Iphimede, according to Pausanias about the Ehoiai. Sophocles links Hecate with crossroads. Hecate is often depicted as triple-forms, which is associated with her crossroads aspect.
Hecate was also associated with sorcery, including Euripides' Medea, in classical times, and later, in Shakespeare's Macbeth.
Source: Early Greek Myth, by Timothy Gantz.