Patriarch Sergius of Moscow

Patriarch Sergius I was the 12th Patriarch of Moscow and all the Rus', from September 8, 1943 until his death on May 15, 1944. He was also the de facto head of the Russian Orthodox Church in 1925–1943, firstly as deputy Patriarchal locum tenens (1925–1937) subsequently as Patriarchal locum tenens (1937–1943).