In Greek mythology, maenads (/ˈmiːnædz/ ^ⓘ; Ancient Greek: μαινάδες [maiˈnades]) were the female followers of Dionysus and the most significant members of his retinue, the thiasus. Their name, which comes from μαίνομαι (maínomai, "to rave, to be mad; to rage, to be angry"), literally translates as 'raving ones'. Maenads were known as Bassarids, Bacchae /ˈbækiː/, or Bacchantes /ˈbækənts, bəˈkænts, -ˈkɑːnts/ in Roman mythology after the penchant of the equivalent Roman god, Bacchus, to wear a bassaris or fox skin.

Often the maenads were portrayed as inspired by Dionysus into a state of ecstatic frenzy through a combination of dancing and intoxication. During these rites, the maenads would dress in fawn skins and carry a thyrsus, a long stick wrapped in ivy or vine leaves and tipped with a pine cone. They would weave ivy-wreaths around their heads or wear a bull helmet in honor of their god, and often handle or wear snakes.

These women were mythologized as the "mad women" who were nurses of Dionysus in Nysa. Lycurgus "chased the Nurses of the frenzied Dionysus through the holy hills of Nysa, and the sacred implements dropped to the ground from the hands of one and all, as the murderous Lycurgus struck them down with his ox-goad". They went into the mountains at night and practised strange rites.

According to Plutarch's Life of Alexander, maenads were called Mimallones and Klodones in Macedon, epithets derived from the feminine art of spinning wool. Nevertheless, these warlike parthenoi ("virgins") from the hills, associated with a Dionysios pseudanor ("fake male Dionysus"), routed an invading enemy. In southern Greece they were described as Bacchae, Bassarides, Thyiades, Potniades,^{[better source needed]} and other epithets.

The term maenad has come to be associated with a wide variety of women, supernatural, mythological, and historical, associated with the god Dionysus and his worship.

In Euripides' play The Bacchae, maenads of Thebes murder King Pentheus after he bans the worship of Dionysus. Dionysus, Pentheus' cousin, himself lures Pentheus to the woods, where the maenads tear him apart. His corpse is mutilated by his own mother, Agave, who tears off his head, believing it to be that of a lion. A group of maenads also kill Orpheus, when he refuses to entertain them while mourning his dead wife.

In ceramic art, the frolicking of Maenads and Dionysus is often a theme depicted on kraters, used to mix water and wine. These scenes show the maenads in their frenzy running in the forests, often tearing to pieces any animal they happen to come across.^{[citation needed]}

German philologist Walter Friedrich Otto writes: