Domagoj (Latin: Domagoi) was Duke of Croatia from 864 to 876, and the founder of the Domagojević dynasty. He usurped the Croatian throne after the death of Trpimir I and expelled his sons. He took a more active role in the Adriatic Sea than his predecessors, encouraged the use of force and waged many wars, specifically with the Arabs, Venice and the East Francia. Domagoj's belligerence and the tolerance and support of piracy caused bad relations with Pope John VIII, which was further worsened after Domagoj showed no mercy to his conspirators. Formally a Frankish vassal, he used to his advantage the Frankish succession crisis and started a successful revolt against Carloman of Bavaria. After his death in 876, Domagoj was succeeded by his son who was deposed and expelled by Zdeslav in 878.