Alan Sharp, who was raised in Greenock, died at his daughter's home in Los Angeles after a long illness, his agents said.
Sharp wrote the screenplays The Hired Hand (1971), starring and directed by Peter Fonda, Ulzana's Raid (1972), a Western with Burt Lancaster; Arthur Penn's Night Moves (1975), starring Gene Hackman and director Sam Peckinpah's final film as a director, The Osterman Weekend (1983). Rob Roy was directed by Michael Caton-Jones and filmed in Scotland.
Sharp also penned the screenplay for Ben-Hur, a mini series aired on ABC in 2010, as well as several other TV projects.
He launched his writing career in 1965 with A Green Tree in Gedde, which won the 1967 Scottish Arts Council Award. The second novel in an uncompleted trilogy, The Wind Shifts, was published in 1968.
Sharp was married four times and his wives included novelist Beryl Bainbridge.
He was born in 1934 in Alyth, near Dundee, and was adopted by a Greenock shipyard worker and his wife. He left school at 14 to work in the shipyards but relocated to London to pursue his writing ambitions.