Sergius of Radonezh
Sergius of Radonezh (, "Sergii Radonezhsky"; 14 May 1314 – 25 September 1392), also known as Sergiy Radonezhsky, Serge of Radonezh and Sergius of Moscow, was a spiritual leader and monastic reformer of medieval Russia. Together with Seraphim of Sarov, he is one of the Russian Orthodox Church's most highly venerated saints.