Léon Jouhaux (July 1, 1879, Pantin, Seine-Saint-Denis – April 28, 1954) was a French trade union leader who received the Nobel Peace Prize in 1951.

Jouhaux's father worked in a match factory in Aubervilliers. His secondary schooling ended when his father's earnings were stopped by a strike. He gained employment at the factory at age sixteen and immediately became an important part of the union. In 1900, Jouhaux joined a strike against the use of the white phosphorus that blinded his father, was dismissed, and worked at a succession of jobs until union influence saw him reinstated.

In 1906, he was elected by the local union as a representative to the General Confederation of Labour (CGT), where his abilities saw him quickly rise through the ranks of organized labour. By 1909 he became interim treasurer, and shortly afterwards became secretary-general of the organization, which he held until 1947. His goals as a trade unionist were the familiar ones of the early labour movement — the eight hour day, the right to union representation and collective bargaining, and paid holidays. During the Popular Front, the 1936 Matignon Agreement, to which he was a signatory, awarded many of these rights to French workers.

André Léon Blum (French pronunciation: [leɔ̃ blym]; 9 April 1872 – 30 March 1950) was a French politician, usually identified with the moderate left, and three times Prime Minister of France.

While in his youth an avid reader of the works of the nationalist writer Maurice Barrès, Blum had little interest in politics until the Dreyfus Affair of 1894, which had a traumatic effect on him as it did on many French Jews. Campaigning as a Dreyfusard brought him into contact with the socialist leader Jean Jaurès, whom he greatly admired. He began contributing to the socialist daily, L'Humanité, and joined the Socialist Party, then called the SFIO. Soon he was the party's main theoretician.

In July 1914, just as the First World War broke out, Jaurès was assassinated, and Blum became more active in the Socialist party leadership. In August 1914 Blum became assistant to the Socialist Minister of Public Works Marcel Sembat. In 1919 he was chosen as chair of the party's executive committee, and was also elected to the National Assembly as a representative of Paris. Believing that there was no such thing as a "good dictatorship", he opposed participation in the Comintern. Therefore, in 1920, he worked to prevent a split between supporters and opponents of the Russian Revolution, but the radicals seceded, taking L'Humanité with them, and formed the SFIC.