Al-Ḥārith ibn Jabalah (Arabic: الحارث بن جبلة‎; [Flavios] Arethas ([Φλάβιος] Ἀρέθας) in Greek sources; Khālid ibn Jabalah (خالد بن جبلة) in later Islamic sources), was a king of the Ghassanids, pre-Islamic Arab Christians who lived on the eastern frontier of the Byzantine Empire. The fifth Ghassanid ruler of that name, he reigned from c. 528 to 569, the longest of any Christian arab ruler and played a major role in the Roman–Persian Wars and the affairs of the Syriac Orthodox Church. For his services to Byzantium, he was made patrikios and vir gloriosissimus.