Hecataeus of Miletus was an aristocratic Greek author from Miletus, active in the late sixth and early fifth centuries BCE. A prominent political figure, he is recorded by Herodotus as having attempted to dissuade the Ionians from revolting against Persia around 499 BCE. His life and work thus bridge the late Archaic and early Classical periods.

He is credited with two major prose works in the Ionic dialect. His Genealogies (or Histories) sought to rationalize Greek mythical traditions, opening with a critical statement on their reliability. His geographical work, the Periodos gēs (Journey around the Earth), described the known world through a coastal survey. It divided the world into Europe and Asia, detailing lands from the Mediterranean to Egypt and Persia. A third work, a map, is sometimes attributed to him.

Hecataeus is a foundational figure in Greek historiography and geography. His critical approach to myth pioneered rational historical inquiry and directly influenced Herodotus, who both used and critiqued his work. His geographical treatise became a standard reference, establishing prose as a vehicle for systematic description.