André Léon Blum (9 April 1872 – 30 March 1950) was a French socialist politician and three-time prime minister.
As a Jew, he was heavily influenced by the Dreyfus affair of the late 19th century. He was a disciple of French Socialist leader Jean Jaurès and after Jaurès' assassination in 1914, became his successor. As Prime Minister in a Popular Front government of the left 1936–37, he provided a series of major economic reforms. Blum declared neutrality in the Spanish Civil War (1936–39) to avoid the civil conflict spilling over into France itself. Once out of office in 1938, he denounced the appeasement of Germany.
When Germany defeated France in 1940, he became a staunch opponent of Vichy France. Tried by Vichy on trumped-up charges, he was imprisoned in the Buchenwald concentration camp. After the war, he resumed a transitional leadership role in French politics, helping to bring about the French Fourth Republic, until his death in 1950.