Karl Kautsky, Czech-German journalist, philosopher, and theologian (d. 1938)
Karl Johann Kautsky (; German: [ˈkaʊtski]; 16 October 1854 – 17 October 1938) was a Czech-Austrian philosopher, journalist, and Marxist theorist. Kautsky was one of the most authoritative promulgators of orthodox Marxism after the death of Friedrich Engels in 1895 until the outbreak of World War I in 1914.

He was the most important socialist theorist during the years of the Second International. He founded the socialist journal Neue Zeit. Following the war, Kautsky was an outspoken critic of the Bolshevik Revolution, engaging in polemics with Vladimir Lenin, Leon Trotsky and Joseph Stalin on the nature of the Soviet state.