Demény is a Hungarian surname. Notable people with the surname include:
Attila Demény (1955–2021), Hungarian-Romanian composer and theatre director (1915–1993), Hungarian musicologist, Béla Bartók specialist László Demény (born 1953), Hungarian fencer Paul Demeny (Pál Demény; 1932–2024), Hungarian demographer and economist
See also Georges Demenÿ (1850–1917), French inventor, chronophotographer and filmmaker Demeny voting, named after Paul Demeny