Yakov Svetoslav

Jacob Svetoslav (Bulgarian: Яков Светослав, Yakov Svetoslav) (ca. 1210s/1220s–1275 or 1276/1277) was a prominent 13th-century Bulgarian noble (bolyarin) of princely Russian origin. Bestowed the title of despot, Jacob Svetoslav was the ruler of a widely autonomous domain of the Second Bulgarian Empire most likely located around Sofia. Seeking further independence and claiming the title of Emperor of Bulgaria, he twice changed allegiance from Bulgaria to the Kingdom of Hungary and vice versa, and the Hungarians recognized his Bulgarian royal rank as their vassal and ruler of Vidin (medieval Bdin).

Jacob Svetoslav's exact origin is not clear, though he is known to have been either a Russian noble himself or the son of one. Jacob or his father most likely arrived in Bulgaria with the wave of Russians fleeing the Mongol invasion of Rus' in the first half of the 13th century. Historian Plamen Pavlov theorizes that Jacob Svetoslav was a descendant of the princes (knyaze) of Kievan Rus', and estimates his birth date as being in the 1210s or 1220s. In the late 1250s, Jacob Svetoslav was already an influential noble. He married a daughter of Theodore II Laskaris from his marriage with Tsar Ivan Asen II's daughter Elena. By 1261, he had become a despot, a high-ranking noble in the Bulgarian hierarchy. The title was awarded to him probably by his own suzerain, the ruler of Bulgaria, rather than a Byzantine emperor, possibly Constantine Tih. Jacob Svetoslav was close to the Bulgarian court and pledged loyalty to Constantine. Thus, the tsar made him the ruler of a domain usually considered to have been south of the Vidin region in the west of the Bulgarian Empire. Byzantine sources indicate his possessions lay "near Haemus", thus close to Sofia, between the Hungarian possessions to the north and Macedonia to the south.

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