Théodore Simon (1872-1961) was a French psychologist who worked with Alfred Binet to develop the Binet-Simon scale, one of the most widely used scales in the world to measure a person's intelligence. This scale was revised in 1908 and 1911, and served as a template for the development of newer scales. Théodore Simon worked at multiple hospitals throughout France, including Sainte-Anne and Dury-les-Amiens. Théodore Simon also worked as the head psychiatrist at St. Yon hospital and as a medical director at Perray-Vaucluse until his retirement in 1936.