Avvákum Petrov (Grigórovo, 1620 or 1621 - Pustoziorsk, 1682) was a Russian ecclesiastic and writer, leader of the schism of the old believers (the raskólniki) against the reform of the patriarch Nikon, which cost him exile in Siberia and in the Circle Arctic polar. For his continued opposition to reforms within the Church, he was sentenced to death at the stake. First apostle and main defender of the Russian schism, he was 62 years old when he was executed. His terrible death came after 15 years of imprisonment, during which he wrote his major works.