William Diehl (December 4, 1924 – November 24, 2006) was an American novelist and photojournalist.
Diehl was fifty years old and already a successful photographer and journalist when he decided he had not heeded his life calling. The day after his 50th birthday he began his first novel, Sharky's Machine, which was made into a movie directed by and starring Burt Reynolds. Diehl later completed eight more novels, including Primal Fear, which became a movie by the same name starring Richard Gere and Edward Norton. Diehl died at Emory University Hospital in Atlanta, Georgia on November 24, 2006, of an aortic aneurism. He was a resident of Woodstock, Georgia at the time of his death and was working on his tenth novel.