William Wister Haines (1908-1989) was an American author, screenwriter, and playwright.

He was born in Des Moines, Iowa in 1908, and graduated from the University of Pennsylvania in 1931 with a degree in engineering. Unable to find work in an engineering field during the Great Depression, he worked as an electric lineman on a railroad running out of Chicago. His experience as a railroad lineman became the basis for his first two books, Slim, and High Tension.

Slim, published in 1934, won him critical and popular acclaim as a writer. The novel was part adventure tale, part social commentary, and part time capsule of the Great Depression, notable for its realism and its on-target portrayal of working class attitudes and language during that period. Slim continues to have an audience today and is a sought-after book, especially among electric power linemen and railfans. In spite of this, the book has been out of print since 1959. In 1937, the book was made into a movie starring Henry Fonda, with Haines writing the screenplay.

His next book, High Tension (1938), was less successful, but his third book, Command Decision (1947) saw him return to critical and popular acclaim. As with his previous books, Command Decision was based on his real-life experiences, this time as an Army Air Force officer during World War II where he worked on the Ultra Project. The book led to a successful play, and was made into a movie in 1948 starring Clark Gable. Command Decision has been called the first important work of fiction about World War II. The book and movie differ from most of the war books and movies from that period, in that Command Decision explores behind the scenes politics, moral conflicts, and psychological effects rather than glorifying war.

The Winter War (1961) was at the time of its publication a popular western and was awarded the Spur Award of the Western Writers of America .

His other books include The Honorable Rocky Slade (1955), Target (1964), The Image (1968), and Ultra (1980). Besides Slim and Command Decision, his filmography includes Black Legion (1937), The Texans (1938), The Eternal Sea (1955), and Torpedo Run (1958).