André Isaac (15 August 1893 Châlons-sur-Marne, France – 9 February 1975 Paris, France), better known as Pierre Dac, was a French humorist. During World War II, Pierre Dac was one of the speakers of the BBC's Radio Londres service to occupied France. He produced a series of satirical songs which were broadcast on the station. After the war, he participated in a comic duet with the humorist Francis Blanche.