The Holy Venerable Theodosius of Tarnovo was a high-ranking 14th-century Bulgarian cleric and hermit. He is credited with establishing hesychasm in the Second Bulgarian Empire. A disciple of Gregory of Sinai, Theodosius founded the Kilifarevo monastery and school near the then-Bulgarian capital Tarnovo and took an important part in the condemning of various heresies during the reign of Tsar Ivan Alexander of Bulgaria.