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.

A very active freemason, initiated in 1926 at "Les Inséparables d'Osiris" lodge in Paris, he created a parodic and slang masonic rite "Le rite des Voyous" still practiced in some French lodges.