The Black Sheep of Whitehall is a 1942 British black-and-white comedy war film, directed by Will Hay and Basil Dearden, starring Will Hay, John Mills, Basil Sydney and Thora Hird in her screen debut. It was produced by Michael Balcon and Ealing Studios.

William Thomson Hay was an English comedian who wrote and acted in a schoolmaster sketch that later transferred to the screen, where he also played other authority figures with comic failings. His film Oh, Mr. Porter! (1937), made by Gainsborough Pictures, is often cited as the supreme British-produced film-comedy, and in 1938 he was the third highest-grossing star in the UK. Many comedians have acknowledged him as a major influence. Hay was also a keen amateur astronomer.