A scholiast, quoting the fifth-century BC historian Hellanicus, tells us that, in addition to the Hesiodic Cyclopes (whom the scholiast describes as "the gods themselves"), and the Homeric Cyclopes, there was a third group of Cyclopes: the builders of the walls of Mycenae. Hesiodic Cyclopes
Hesiod, in the Theogony (c. 700 BC), described three Cyclopes: Brontes, Steropes, and Arges, who were the sons of Uranus (Sky) and Gaia (Earth), and the brothers of the Titans and Hundred-Handers, and who had a single eye set in the middle of their foreheads. They made for Zeus his all-powerful thunderbolt, and in so doing, the Cyclopes played a key role in the Greek succession myth, which told how the Titan Cronus overthrew his father Uranus, and how in turn Zeus overthrew Cronus and his fellow Titans, and how Zeus was eventually established as the final and permanent ruler of the cosmos. The names that Hesiod gives them: Arges (Bright), Brontes (Thunder), and Steropes (Lightning), reflect their fundamental role as thunderbolt makers. As early as the late seventh-century BC, the Cyclopes could be used by the Spartan poet Tyrtaeus to epitomize extraordinary size and strength.According to the accounts of Hesiod and mythographer Apollodorus, the Cyclopes had been imprisoned by their father Uranus. Zeus later freed the Cyclopes, and they repaid him by giving him the thunderbolt. The Cyclopes provided for Hesiod, and other theogony-writers, a convenient source of heavenly weaponry, since the smith-god Hephaestus—who would eventually take over that role—had not yet been born.
Euripides calls their walls "heaven-high" (οὐράνια), describes "the Cyclopean foundations" of Mycenae as "fitted snug with red plumbline and mason’s hammer", and calls  Mycenae "O hearth built by the Cyclopes". He calls Argos "the city built by the Cyclopes", refers to "the temples the Cyclopes built" and describes the "fortress of Perseus" as "the work of Cyclopean hands". Callimachus
For the third-century BC poet Callimachus, the Hesiodic Cyclopes Brontes, Steropes and Arges, become assistants at the forge of the smith-god Hephaestus. Callimachus has the Cyclopes make Artemis bow, arrows and quiver, just as they had (apparently) made those of Apollo. Callimachus locates the Cyclopes on the island of Lipari, the largest of the Aeolian Islands in the Tyrrhenian Sea off the northern coast of Sicily, where Artemis finds them "at the anvils of Hephaestus" making a horse-trough for Poseidon:

And the nymphs were affrighted when they saw the terrible monsters like unto the crags of Ossa: all had single eyes beneath their brows, like a shield of fourfold hide for size, glaring terribly from under; and when they heard the din of the anvil echoing loudly, and the great blast of the bellows and the heavy groaning of the Cyclopes themselves. For Aetna cried aloud, and Trinacia cried, the seat of the Sicanians, cried too their neighbour Italy, and Cyrnos therewithal uttered a mighty noise, when they lifted their hammers above their shoulders and smote with rhythmic swing the bronze glowing from the furnace or iron, labouring greatly.