Marguerite Long (13 November 1874 – 13 February 1966) was a French pianist and teacher. Marguerite Marie-Charlotte Long was born in Nîmes. She studied with Henri Fissot at the Paris Conservatoire, taking a Premier prix in 1891, and privately with Antoine François Marmontel. From 1906 to 1940 she taught at the Paris Conservatoire, and in 1920 she succeeded Louis Diémer as professor of piano. She also taught privately. Marguerite Long died in Paris in 1966, aged 91.