Hiero I was the brother of Gelo and tyrant of Syracuse from 478 to 467 BC.

During his reign he greatly increased the power of Syracuse. He removed the inhabitants of Naxos and Catana to Leontini, peopled Catana (which he renamed Aetna) with Dorians, concluded an alliance with Acragas (Agrigentum) and espoused the cause of the Locrians against Anaxilaus, tyrant of Rhegium.

Helmet with inscription commemorating the victory of Hiero I of Syracuse over the Etruscans 474 BC

His most important achievement was the defeat of the Etruscans at the Battle of Cumae (474 BC), by which he saved the Greeks of Campania from Etruscan domination. A bronze helmet (now in the British Museum), with an inscription commemorating the event, was dedicated at Olympia. Though despotic in his rule Hiero was a liberal patron of literature. He died at Catana in 467.

See Diod. Sic. xi. 38-67; Xenophon, Hiero, 6. 2; E. Lübbert, Syrakus zur Zeit des Gelon und Hieron (1875);