Joseph-Marie-Auguste Caillaux (March 30, 1863 - November 21/22, 1944) was a major French politician of the Third Republic. The leader of the Radicals, he favored a policy of conciliation with Germany during his premiership from 1911 to 1912, which led to the maintenance of the peace during the Second Moroccan Crisis of 1911.
In 1914 he fell into disgrace when his wife shot the editor of Le Figaro when he threatened to print love letters between her and Caillaux from when she was still married to another man. She was acquitted, however, and Caillaux became the leader of a peace party in the Assembly during World War I. This led to his arrest and trial for treason in 1918. Again rehabilitated after the war, Caillaux served at various times in the left wing governments of the 1920s.