Isaac Deutscher (Polish: Izaak Deutscher; 3 April 1907 – 19 August 1967) was a Polish Marxist writer, journalist and political activist who moved to the United Kingdom before the outbreak of World War II. He is best known as a biographer of Leon Trotsky and Joseph Stalin and as a commentator on Soviet affairs.
His scholarly biographies of Trotsky and Stalin have received widespread acclaim,[1][2][3][4] with several reviewers ranking his three-volume Prophet trilogy among the greatest of political biographies;[5][6][7] some criticism has been directed at his overly sympathetic tone for the subject matter.[8][9] His three-volume biography of Trotsky was also highly influential among the British New Left in the 1960s and 1970s.[10]