Joseph Smith Fletcher (7 February 1863 - 30 January 1935) was a British journalist and author. He wrote more than 230 books on a wide variety of subjects, both fiction and non-fiction. He was one of the leading writers of detective fiction in the "Golden Age".
Fletcher was born in Halifax, West Yorkshire, the son of a clergyman. He was educated at Silcoates School in Wakefield. After some study of law, he became a journalist. His first books published were poetry. He then moved on to write numerous works of historical fiction and history, many dealing with Yorkshire, which led to his selection as a fellow of the Royal Historical Society. Fletcher wrote several novels of rural life in imitation of Richard Jefferies, beginning with The Wonderful Wapentake (1894). Michael Sadleir stated that Fletcher's historical novel When Charles I Was King (1892) was his best work. In 1914 he wrote his first detective novel and went on to write more than a hundred, many featuring the private investigator Ronald Camberwell.
He was married to the Irish writer Rosamond Langbridge, with whom he had one son.