Novelist and screenwriter whose comedic fiction works include The Magic Christian (1959) and Candy (1958). He also contributed to the screenplays for Dr. Strangelove (1964), The Cincinnati Kid (1966), and The Loved One (1965).
He attended Southern Methodist University, but left college to serve as a lieutenant in the U.S. Army during World War II. He later graduated from Northwestern University with a degree in philosophy.
He received an O. Henry Award for his 1962 short story, "The Road Out of Axotle."
He married model Pud Gadiot in 1952. The couple divorced two years later, and Southern married another model, Carol Kauffman, in July of 1956.
He wrote the screenplay for the 1967 film, Casino Royale, starring David Niven.