Sergius of Radonezh was a 14th-century Russian Orthodox monk, priest, and abbot who became a central figure in the spiritual revival of his era. Born Bartholomew to a boyar family, he eventually settled in the forest near Moscow to live an ascetic life. He founded the Trinity Lavra of St. Sergius, which grew into a major monastic center. Recognized as a wonderworker, he exerted immense influence over the Russian Church and is remembered for his commitment to manual labor and his role in establishing numerous monasteries across the region.