Constantine of Kostenets
Constantine of Kostenets (Bulgarian: Константин Костенечки, romanized: Konstantin Kostenechki; c. 1380 – after 1431), also known as Constantine the Philosopher (Serbian: Константин Филозоф / Konstantin Filozof), was a medieval Bulgarian 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).