Dormoy () is a French surname. Notable people with the surname include:
Pierre Jacques Dormoy (1825–1892), French Protestant engineer and inventor Étienne Dormoy (1885–1959), French aeronautical engineer and aircraft designer Marx Dormoy (1888–1941), French socialist politician. Marcelle Dormoy (1895–1976), French fashion designer active 1910s to 1950
See also Dormoy Bathtub, a racing aeroplane invented by Etienne Dormoy in the 1920s Marx Dormoy (Paris Métro), a station of the Paris Métro named after the politician