People of the Revolution and the USSR
- Wilhelm Liebknecht Wilhelm Liebknecht Co-founder of the Eisenach party and drafter of the Gotha Programme
- August Bebel August Bebel Co-founder of the SPD who led the German workers' movement for over 40 years, the 'shadow emperor' of the working class
- Paul Lafargue Paul Lafargue Marx's son-in-law, author of The Right to Be Lazy, first socialist deputy in the French parliament
- Jules Guesde Jules Guesde Veteran founder of French Marxist socialism who entered the Union sacrée government in 1914
- Pavel Borisovich Axelrod Павел Борисович Аксельрод Theorist of the mass workers' party: the argument that lost to Lenin's vanguard
- Victor Adler Victor Adler Founder and leader of Austrian Social Democracy who could not stop the war in 1914 and backed it
- Keir Hardie Keir Hardie Former miner who founded the British Labour Party and opposed the First World War to the end, urging an anti-war general strike
- Dimitar Nikolov Blagoev Димитр Николов Благоев Founder of Bulgarian socialism who organized Russia's first Marxist circle
- Clara Zetkin Clara Zetkin Creator of International Women's Day, she set women's liberation at the heart of class struggle
- Jean Jaurès Jean Jaurès French socialist leader who united the left, founded L'Humanité, and was assassinated fighting to prevent the Great War
- Marcel Sembat Marcel Sembat French Socialist deputy who joined the Union sacrée government as Minister of Public Works in 1914
- Émile Vandervelde Émile Vandervelde Chairman of the International Socialist Bureau who led the Second International and joined Belgium’s wartime government in 1914
- Alexander Nikolayevich Potresov Александр Николаевич Потресов One of the six who built Iskra: the Menshevik theorist who parted with Lenin
- Fyodor Ilyich Dan Фёдор Ильич Дан Menshevism's theoretical pillar who stood for democratic socialism against Lenin
- Julius Osipovich Martov Юлий Осипович Мартов Lenin’s oldest friend and most principled adversary
- Elizabeth Gurley Flynn Elizabeth Flynn "East Side Joan of Arc": from the IWW's Rebel Girl to first woman chair of the CPUSA