Mithridates III Antiochus Epiphanes (Greek: Μιθριδάτης Ἀντίοχος ὀ Ἐπιφανής, flourished 1st century BC) was a prince who served as a King of Commagene.
Mithridates III, sometime after 30 BC, had married his paternal cousin Iotapa, a Princess of Media Atropatene who was a daughter of Artavasdes I of Media Atropatene.
Iotapa bore Mithridates III one son called Antiochus III and two daughters both called Iotapa.
One daughter called Iotapa married King Sampsiceramus II of Emesa, Syria and another Iotapa, later married and ruled with her brother Antiochus III.
When he died in 12 BC, Antiochus III of Commagene became King.