Louis Loucheur (August 12, 1872 in Roubaix, Nord – November 22, 1931 in Paris) was a French politician in the Third Republic, at first a member of the conservative Republican Federation, then of the Democratic Republican Alliance and of the Independent Radicals.
Coming from a background in the arms industry, Loucheur became Minister of Munitions in September 1917. He replaced Albert Thomas and served as munitions minister until November 26, 1918 when he became Minister of Industrial Re-construction where he remained until January 20, 1920.
He was the principal economic advisor for Georges Clemenceau at the 1919 Paris Peace Conference. The product of this conference was the controversial Treaty of Versailles.
Loucheur was briefly Minister of Commerce, Industry, Posts, and Telegraphs under Raymond Poincaré in 1924.
He also served as Minister of Finance in Aristide Briand's seventh Government during 1925 and 1926.
In Édouard Herriot's Second Ministry Loucheur served as Minister of Commerce and Industry and from June 1928 to February 1930.. He then served again under Poincaré as Minister of Labour, Hygiene, Welfare Work, and Social Security Provisions.