Lebedus or Lebedos (Greek: Λέβεδος) was one of the twelve cities of the Ionian League, located south of Smyrna, Klazomenai and neighboring Teos and before Ephesus, which is further south. It was on the coast, ninety stadia (16.65 km) to the east of Cape Myonnesus, and 120 (22.2 km) west of Colophon.
The city was built on and around a very small peninsula (175 m long, reaching a height of 61 m and with an isthmus 201 m wide), which is called the Kısık Peninsula today and depends on the coastal township of Ürkmez, part of Seferihisar locality, a district center depending on the province seat of İzmir.
Lebedus is also a Roman Catholic Titular see of Asia Minor, in the suffragan of Ephesus.
According to Pausanias, the town was inhabited by Carians when the Ionian Greeks immigrated there under the guidance of Andræmon, a son of Codrus. Strabo, however, states that it was colonized by Andropompus and that it previously bore the name of Artis in Lydia. Lebedos became a flourishing city thanks to its commerce, and was famous for its mineral springs. But it was one of the smaller cities of the Ionian League, handicapped by the limited space of its hinterland and a comparatively unsuitable port.