Konstantin, Filozof, active 14th century-15th century

Constantine of Kostenets (Bulgarian: Константин Костенечки, romanized: Konstantin Kostenechki; c. 1380 – after 1431), also known as Constantine the Philosopher (Serbian: Константин Филозоф, romanized: Konstantin Filozof), was a medieval Bulgarian scholar, writer and chronicler, who spent most of his life in the Serbian Despotate. He is best known for his biography of Serbian despot Stefan Lazarević, which George Ostrogorsky described as "the most important historical work of old Serbian literature", and for writing the first Serbian philological study, Skazanije o pismeneh (A History on the Letters). He followed the writing style of the Old Serbian vita, first made popular in the Serbian scriptoria of the 12th century.