John Uroš was a 14th-century Serbian royal and ruler of Thessaly who later entered monastic life. Born around 1350 to Emperor Simeon Uroš and Thomais Orsini, he belonged to the Nemanjić dynasty. After governing the region from approximately 1370 to 1373, he abdicated his political authority in favor of a relative. He subsequently joined the monastic community at Meteora, where he lived for the remainder of his life under the name Joasaph.