Deiotarus (died 40 BC)

Roman tetrarch (ruler of one of four divisions) of the territory of Galatia, in central Asia Minor. In return for help during the third war against Mithridates VI, King of Pontus, Pompey gave him the title of king and enlarged his territory to include Lesser Armenia. Deiotarus sided with Pompey in the civil war and fled with him after he was defeated by Caesar at the Battle of Pharsalus 48 BC. The following year he was pardoned by Caesar and, although deprived of some territory, was left with the royal title.

Later accused by his own grandson of having attempted to murder Caesar, Deiotarus was defended by the orator Cicero, but before the case ended Caesar was murdered, and no verdict was reached. Mark Antony restored his confiscated territory in return for a large bribe, and on the renewal of civil war Deiotarus joined Brutus and Cassius. After the Battle of Philippi 42 BC he supported the Second Triumvirate of Augustus, Mark Antony, and Lepidus, and lived out the remainder of his reign in peace.