Despot Jacob Svetoslav

Jacob Svetoslav was a Bulgarian despot of Russian origin who ruled in north-western Bulgaria during the second half of the thirteenth century. Ivan Asen II appointed him governor of a region in the western Balkan Mountains after the Tatar invasion of the Russian principalities in 1240. According to historical sources, his possessions lay mainly in north-western Bulgaria, but their exact boundaries are unknown.

During the struggle for power after Ivan Asen II's death, Jacob Svetoslav supported the boyar Constantine Asen in his contest for the Tarnovo throne. In 1262–1263 he took part in a war against Byzantium, which ended unsuccessfully for Bulgaria. In 1266, following the Hungarian invasion, he became a Hungarian vassal, but later, in 1273, he renounced his dependence on Hungary. In 1275, after Tsarina Maria Palaiologina offered to adopt him, he arrived in Tarnovo and was proclaimed the tsarina's second son. Nevertheless, he died soon afterwards, probably from poisoning.