Klazomenai (also spelled Clazomenae, Greek: Κλαζομεναί, modern-day Kilizman in Urla near İzmir in Turkey) was an ancient Greek city of Ionia and a member of the Ionian Dodecapolis (Confederation of Twelve Cities), it was one of the first cities to issue silver coinage.

Klazomenai is located in modern Urla (Vourla in Greek) on the western coast of Anatolia, on the southern coast of the Gulf of İzmir, at about 20 miles west of İzmir. The city was originally located on the mainland, but probably during the early fifth-century Ionian Revolt from the Persians, it was moved to an island just off the coast, which Alexander the Great eventually connected to the mainland with a causeway. The location of the city-around a harbour, backed by a coastal plain and low hills to the south provided a number of locations for settlement, and as such, settlements did shift from location to location over time. This can be shown by the island of Karantina, located to the north of the settlement area-which became settled at certain points in the history of Klazomenai.