Ariobarzanes (in Greek Ἀριoβαρζάνης), (Old Persian: Ariyabrdhna, Ariyaubrdhna) Ariobarzan or spelled as Ario Barzan or Aryo Barzan, perhaps signifying "exalting the Aryans" (death: crucified in c. 362 BCE), sometimes known as Ariobarzanes I of Cius, was a Persian Satrap of Phrygia and military commander, leader of an independence revolt, and the first known of the line of rulers of the Greek town of Cius from which were eventually to stem the kings of Pontus in the 3rd century BCE. Ariobarzanes was apparently a cadet member of the Achaimenid dynasty, specifically its branch which had settled to hold Dascylium of Hellespont in the 470s BCE. Cius is located near Dascylium, and Cius seemingly was a share of family holdings for the branch of Ariobarzanes.
Ariobarzanes' one predecessor was a (kinsman) named Mithradates (possibly Mithradates, Satrap of Cappadocia). The archaeologist Walther Judeich claims that Ariobarzanes was that Mithradates' son, but Brian C. McGing refutes that specific filiation. Seemingly, no classical source itself calls them son and father, the filiation being a later reconstruction on basis of successorship.
Pharnabazus, Satrap of Phrygia (fl. 413 - 373 BCE), son of Pharnaces of Phrygia, is indicated to have shared his rule and territories with his brothers in the late 5th century BCE when Pharnabazos had recently succeeded to the position. Mithradates, Satrap of Cappadocia, might have been one of such brothers. Ariobarzanes of Cius might have also been one of those brothers.
The classical source Appianus relates that Ariobarzanes was of a cadet line of the family of the Persian Great King Dareios (Darius the Great).