Aratius (Greek: 'Αράτιος, d. 552) was an Armenian military commander of the 6th century. He served at first the Sasanian Empire, then defected to the Byzantine Empire. He is primarily known for his activities in the Iberian War and the Gothic War. He was eventually killed in an ambush. Primary sources about him include Choricius of Gaza and Procopius of Caesarea.
Aratius was a native of Persian Armenia. He was a brother of Isaacius (Isaac) and Narses. His brother should not be confused with the famous general Narses. Choricius of Gaza describes Aratius as originating from a good family and having distinguished brothers. He does not identify this family. Modern historians suggest that they could be part of the Kamsarakan family, also ancestral to Narses.
Aratius and Narses are first mentioned in 527. They were fighting for the Sassanid Empire in the Iberian War (526-532). The two of them managed to win a victory over the Byzantine commanders Belisarius and Sittas. The battle is briefly described by Procopius: "And the Romans, under the leadership of Sittas and Belisarius, made an inroad into Persarmenia, a territory subject to the Persians, where they plundered a large tract of country and then withdrew with a great multitude of Armenian captives. These two men were both youths and wearing their first beards, body-guards of the general Justinian, who later shared the empire with his uncle Justin I. But when a second inroad had been made by the Romans into Armenia, Narses and Aratius unexpectedly confronted them and engaged them in battle. These men not long after this came to the Romans as deserters, and made the expedition to Italy with Belisarius; but on the present occasion they joined battle with the forces of Sittas and Belisarius and gained the advantage over them."