August William Derleth (born February 24, 1909 - died July 4, 1971) was an American writer and anthologist. He also used the pseudonym Stephen Grendon. Co-founder of Arkham House with Donald Wandrei.
Derleth was a member of the Lovecraft Circle of writers, and made his own contributions to H. P. Lovecraft's Cthulhu Mythos. He also wrote Sherlock Holmes pastiches about a detective named "Solar Pons." Derleth wrote a series of books about life in Wisconson collectively known as the Sac Prairie Saga.
August Derleth's short fiction was adapted for the television programs Thriller, hosted by Boris Karloff, and Night Gallery, hosted by Rod Serling.