Simeon Uroš (, ; 1326–1370), nicknamed Siniša (Синиша), was a self-proclaimed Emperor of Serbs and Greeks, from 1356 to 1370. He was son of Serbian King Stephen Uroš III and Byzantine Princess Maria Palaiologina. Initially, he was awarded the title of despot in 1346, and appointed governor of southern Epirus and Acarnania in 1347 by his half-brother, Serbian Emperor Stephen Dušan. After Dušan's death in 1355, the Serbian throne passed to Dušan's son Stephen Uroš V, but despot Simeon decided to seize the opportunity in order to impose himself as co-ruler and lord of all southern provinces of the Serbian Empire. That led him to conflict with his nephew in 1356, when Simeon started to expand his control in southern regions of the Empire, trying to take Thessaly and Macedonia. He proclaimed himself Emperor of the Serbs and Greeks, creating a separate state, centered in regions of Thessaly and Epirus, where he ruled until his death in 1370. He was succeeded by his son Jovan Uroš. Early life Simeon Uroš was the son of King Stephen Uroš III (r. 1322–1331) by his second wife, Maria Palaiologina, the daughter of the Byzantine prince and rebel John Palaiologos who had joined Stephen's raids in Macedonia in 1326, the same year Simeon Uroš was born. His older, half-brother, Dušan was crowned "Young king" (designated heir) in 1322 during the crowning of their father. Stephen Dušan's reign Stephen Dušan was crowned King in September 1331, after months of civil war. Dušan exploited the Byzantine civil war and made major gains beginning in 1342. Having all of Macedonia under his rule, Stephen Dušan was proclaimed "Emperor of Serbs and Greeks" in September 1345, then crowned as such in April 1346. Dušan, as an emperor, granted Byzantine titles upon his magnates. Simeon Uroš and Jovan Asen were given the despot title, while others were given the sebastokrator and kesar titles. With the Serbian conquest of Epirus, Acarnania and Thessaly by 1348, Simeon Uroš was given the governorship of Epirus and Thessaly. Simeon Uroš consolidated his position with the local aristocracy by marrying Thomais Orsini, the daughter of the former ruler of Epirus, John II Orsini. Claim to the Serbian throne and independence Simeon Uroš's relatively uneventful governorship was interrupted when, shortly after Dušan's death in 1355, his brother-in-law Nikephoros II Orsini, the deposed ruler of Epirus, reappeared in Greece and gained the support of the nobility