Hicetas of Syracuse was a Pythagorean philosopher active in the 4th century BCE in Sicily. He was part of the later Pythagorean tradition in the Greek communities of southern Italy and Sicily. No details of his personal life or education survive, and he is not known to have authored any specific texts that have come down to us. His ideas are preserved only through reports by later ancient writers.

His historical importance rests on a single, significant cosmological theory attributed to him. According to the Roman philosopher Cicero, Hicetas proposed that the Earth rotates daily on its own axis from west to east, while the sphere of the fixed stars remains motionless. This same idea is also credited by ancient sources to other Pythagoreans, such as Ecphantus of Syracuse and Philolaus of Croton. Hicetas’s theory represents an early challenge to the more common ancient view of a completely stationary Earth. Modern scholars see him as part of a minor but important strand of pre-modern astronomical thought that considered the motion of the Earth, long before the Copernican revolution. His existence also illustrates the geographical spread and enduring activity of Pythagorean philosophy in the western Greek world during the Classical period.