Vonones I of Parthia (ΟΝΩΝΗΣ on his coins) ruled the Parthian Empire from about 8 to 12 AD. He was the eldest son of Phraates IV of Parthia (ruled c. 37–2 BC) and was sent to Rome as a hostage in the 20s BC as surety for a treaty his father made with Augustus.
After the assassination of Orodes III in about the year 6 AD, the Parthians applied to Augustus for a new King from the house of Arsaces. Augustus sent them Vonones I, but he could not maintain himself as King; he had been educated as a Roman, and was despised by the Parthian nobility as a slave of the Romans. Another member of the Arsacid house, Artabanus II (ruled c. 10–38), who was living among the Dahan nomads in the east of Parthia, was invited to the throne. In a civil war he defeated and expelled Vonones I.
The coins of Vonones I date from 8 to 12 AD and bear the inscription "King Vonones, conqueror of Artabanus" commemorating a temporary victory over his rival. Those of Artabanus II begin in the year 10. In about the year 12 Vonones I fled into Armenia and became King there. But Artabanus II demanded his deposition, and as Augustus did not wish to begin a war with the Parthians he removed Vonones I into Syria, where he was kept in custody, though in a kingly style. Later he was moved to Cilicia, and when he tried to escape in about 19 AD, he was killed by his guards.