Rheomithres was a Persian noble. He joined in the Great Satraps' Revolt of the western provinces from Artaxerxes II, in 362 BC, and was employed by his confederates to go to Tachos, king of Egypt, for aid. He returned to Asia, with 500 talents and 50 warships and he is supposed to have left his wife, his children and the children of his friends at Tachos as a guarantee for the valuable assistant. Nevertheless, Rheomithres betrayed the rebels and he invited a number of them in a meeting. On their arrival, he arrested them, and despatched them in chains to Artaxerxes to receive the bounties, thus making his own peace at court. Rheomithres, was in command of a body of 2000 cavalry, consisted of Medes and Bactrians, at the battle of the Granicus, in 334 BC. He was killed in the next year at the battle of Issus.