Grigorii Zinoviev (1883-1936) was a leading member of the Bolshevik Party and a close associate of Lenin in the period leading up to the October 1917 Revolution in Russia. Born in the Ukraine to Jewish dairy farmers, Zinoviev joined the Russian Social Democratic Labor Party (RSDLP) in 1901. In 1903, following the split between the Bolshevik and Menshevik factions, he sided with Lenin and the Bolsheviks.

He was elected to the RSDLP Central Committee in 1908 and subsequently worked closely with Lenin in exile. Zinoviev was known for his outstanding speaking ability. He took part in the Zimmerwald conference and co-authored with Lenin a work aimed at explaining the crisis in the Second International. After the Feburary 1917 revolution which overthrew the Romanov monarchy, he returned with Lenin and other Bolshevik exiles to Russia.

Along with Lev Kamenev he opposed the October 1917 armed seizure of power by the Bolsheviks. Following the revolution he became head of the Petrograd Soviet and Chairman of the Communist International from its founding until 1926. He was a member, along with Kamenev and Stalin, of the Triumvirate that arrayed itself against Leon Trotsky from 1923-1925.

In 1926 Zinoviev and Kamenev broke with Stalin and allied themselves with Trotsky in his struggle against the rising bureaucracy, though they maintained differences with Trotsky on a number of key questions, including permanent revolution. In late1927, facing expulsion from the party, Zinoviev and Kamenev capitulated to Stalin.

There followed a series of arrests, re- expulsions and recantations. In 1935 Zinoviev was sentenced to 10 years hard labor for "moral complicity" in the murder of Kirov. In 1936 Zinoviev and Kamenev were defendants in the first Moscow frame-up trial, standing accused of forming a terrorist organization allied with Trotsky. They were both found guilty and executed in August 1936.