Pacorus I of Parthia (died 38 BC) was the son of king Orodes II of the Parthian Empire. It is possible that he was co-ruler with his father for at least part of his father's reign. He was the brother-in-law of king Artavasdes II of Armenia.

Following the defeat of the Roman general Marcus Licinius Crassus at the Battle of Carrhae in 53 BC, Pacorus launched an invasion of Syria in 51 BC, briefly conquering the Roman territory before being driven out by Cassius.

Pacorus invaded Syria again in 40 BC in alliance with the Roman rebel Quintus Labienus . The Roman garrisons defected to Labienus and the combined armies defeated the forces of the Roman governor Saxa, who lost most of his troops as he retreated to Antioch. With the Imperial forces routed, Pacorus and Labienus occupied the whole of Palestine and Asia Minor, with the exception of a few cities that held out, including Tyre. In Judea, Pacorus deposed king John Hyrcanus II and appointed his nephew Antigonus king in his place.

In 39 BC, a Roman counterattack under Publius Venditius killed Labienus in a battle in the Taurus Mountains and recovered Asia Minor. Pacorus returned to Syria in 38 BC but was killed in an attack on a Roman camp.

References

• Plutarch, Life of Crassus.
• Dio Cassius, xlviii–xlix.