Alfred George Deller, CBE (31 May 1912 – 16 July 1979), was an English singer and one of the main figures in popularising the return of the countertenor voice in Renaissance and Baroque music during the 20th century.
He is sometimes referred to as the "godfather of the countertenor". His style in singing lute song, with extensive use of rubato and extemporised ornamentation, was seen as radical and controversial in his day but is now considered the norm.
Deller was an influential figure in the renaissance of early music: an early proponent of original instrument performance and one of the first to bring this form to the popular consciousness through his broadcasts on the BBC. He also founded the Stour Music Festival in 1962, one of the first and most important early music festivals in the world.