Gregory Tsamblak was a Bulgarian cleric and scholar who lived from approximately 1365 to 1420. Born in Veliko Tarnovo, he became a prominent figure in the Eastern Orthodox Church, serving as a writer, hagiographer, and bishop. His ecclesiastical career spanned several regions, including Bulgaria, Serbia, Moldavia, and Lithuania. He is most notably remembered for his role as the Metropolitan of Kyiv, a position he attained during a period of significant political and religious shifts in Eastern Europe.