Utilising primary sources in Russian archives, relevant research on Russian and Soviet history and memoirs from contemporaries, this book examines the life of Grigory Zinoviev (1883–1936). Grigory Zinoviev was Vladimir Lenin’s closest political companion in the decade before the Russian Revolution in 1917. After the revolution, Zinoviev became one of the foremost leaders of the new Soviet state. For several years, he was a member of the Politburo of the Communist Party of the Soviet Union. He was the party leader in Petrograd/Leningrad (St. Petersburg), and he was the president of the Communist International. However, he lost the power struggle with Joseph Stalin and ended up as the most prominent defendant at the first Moscow trial, where he was sentenced to death and executed. This book provides for the first time a complete presentation in English of the life and work of this important politician. This volume presents Zinoviev’s life as a politician, as well as his private life and seeks to bring new knowledge both about Zinoviev himself and more generally about Russian and Soviet history during Zinoviev’s lifetime. This volume is perfect for students and scholars alike interested in the history of Russia, the Soviet Union and the history of communism.