Dzerzhinsky, Feliks Edmundovich, 1877-1926, Russian Bolshevik leader, organizer, and first chairman (1917-21) of the Cheka (see secret police). He was the son of Polish aristocrats. Under his direction, the reign of terror against anti-Bolsheviks reached its height in 1918. Dzerzhinsky also headed the agencies that succeeded the Cheka (the OGPU and the GPU) and held other high posts.