Horace Annesley Vachell (1861–1955) was a prolific English writer of novels, plays, short stories, essays and autobigraphical works.

Born in Sydenham, Kent on 30 October 1861, he was educated at Harrow and Sandhurst. After a short period in the Rifle Brigade, he went to California where he became partner in a land company and married Lydie Phillips, his partner's daughter. His wife died in 1895 after the birth of their second child.

After 17 years abroad, by 1900 Vachell was back in England and went on to write over 50 volumes of fiction including a popular school story, The Hill (1905), which gives an idealised view of life at Harrow and of the friendship between two boys. He also wrote 14 plays, the most successful of which in his lifetime was Quinneys (1914), made into a film in 1927. Another play, The Case of Lady Camber (1915), was the basis for Hitchcock's film Lord Camber's Ladies (1932). His last autobiographical book, More from Methuselah (1951), was published in the year of his 90th birthday.

Although some fiction, like the stories in Bunch Grass (1912), is set in American ranching country, much of his writing concerns a comfortably prosperous English way of life which was echoed in his beautiful old house near Bath and his old-fashioned, distinguished appearance and manner. While he was a fellow of the Royal Society of Literature, and compared at his best with Galsworthy, he has never been considered a major writer. He died on 10 January 1955 in Somerset.