An Old Bolshevik (старый большевик) was a member of the Bolsheviks before the Russian Revolution.

Josef Stalin removed nearly all Old Bolsheviks from power during the Great Purges of the 1930s. Most were executed for treason after show trials, some were sent to labor camps, and a few (e.g., Alexandra Kollontai) were sent abroad as ambassadors, effectively preventing them from participating in the central government.

Many communist opponents of Stalin, most notably the Trotskyists, cite this fact in support of their argument that Stalin betrayed the aims of the revolution for his own gain.

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In a narrower sense, the term "Old Bolshevik", as well as the expression Bolshevik Old Guard (старая большевистская гвардия), was also a self-description of bolshevik leaders who opposed Leon Trotsky immediately after the Russian Revolution, alluding at the fact that in a certain time period Trotsky sided with the mensheviks against Vladimir Lenin.

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A number of things in the Soviet Union bore the name "Old Bolshevik", such as several steamships and motorboats, a publishing house, and several settlements.