King Mithridates III of Parthia ruled the Parthian Empire c. 57–54 BC. With the assistance of his brother Orodes he murdered his father Phraates III. He was made king of Media and waged war against his brother, but was soon deposed on account of his cruelty. He took refuge with Aulus Gabinius, the Roman proconsul of Syria. He advanced into Mesopotamia, but was beaten at Seleucia by Orodes' general Surena, fled into Babylon, and after a long siege was taken prisoner and killed in 54 BC by Orodes.