In Greek mythology and later Roman mythology, the Cyclopes (/saɪˈkloʊpiːz/ sy-KLOH-peez; Greek: Κύκλωπες, Kýklōpes, "Circle-eyes" or "Round-eyes";^[1] singular Cyclops /ˈsaɪklɒps/ SY-klops; Κύκλωψ, Kýklōps) are giant one-eyed creatures.^[2] Three groups of Cyclopes can be distinguished. In Hesiod's Theogony, the Cyclopes are the three brothers, Brontes, Steropes, and Arges, who made Zeus's weapon, the thunderbolt. In Homer's Odyssey, they are an uncivilized group of shepherds, the brethren of Polyphemus encountered by Odysseus. A third group of Cyclopes reputedly built the Cyclopean walls of Mycenae and Tiryns.

In Cyclops, the fifth-century BC play by Euripides, a chorus of satyrs offers comic relief based on the encounter of Odysseus and Polyphemus. The third-century BC poet Callimachus makes the Hesiodic Cyclopes the assistants of smith-god Hephaestus, as does Virgil in the Latin epic Aeneid, where he seems to equate the Hesiodic and Homeric Cyclopes.

From at least the fifth century BC, Cyclopes have been associated with the island of Sicily and the volcanic Aeolian Islands.