Aras, Araks, Arax, Araxes, or Araz (Persian: ارس, Azerbaijani: Araz), is a river rising in Anatolia in Turkey, flowing along the Turkey-Armenia border, then along the Azerbaijan-Iran border, entering Azerbaijan, and falling into Kura river as a right tributary. Total length is about 600 miles.

Aras was chosen as the border limit between Persia and Russia in the Treaty of Golestan in 1813 by which the whole area north of that river was cut off from Iran and annexed to Russia. Iran and the Soviet Union later built a joint dam on this river at Poldasht area.

The Hellenized form Araxes is found in the name of the Kura-Araxes culture, a prehistoric people which flourished in the valleys of the Kura and Aras.