The son of factory workers in Detroit, Wexler had a flair for creating realistic down-to-earth characters with rough edges and a degree of grit. His career was dogged, though, by periods of mental illness which resulted in manic outbursts of temperament and which led to a prison sentence when, on a flight from New York to San Francisco in 1972, he made threats against President Richard Nixon. His later Hollywood career achieved notoriety when he had a well- publicised feud with Sylvester Stallone, whom he accused of mutilating his script for a sequel to Saturday Night Fever.
Born in Detroit in 1926 and educated at Harvard College, Wexler moved to New York in 1951 and worked in an advertising agency as a copy-writer. He started to write plays in his spare time, and by the mid-Sixties several of them had been produced off-Broadway and in regional theatres.
His breakthrough came when he wrote the script for Joe (1970), a low- budget film about a construction worker who forms an uneasy relationship with a businessman whose daughter (Susan Sarandon in her screen debut) has become involved with drug-addicts. Directed by John Avildson, the film became a cult hit, bringing fame to Peter Boyle, who played the title character. Howard Thompson, of The New York Times, called Wexler's script "uncannily knowing and observant in staking out and stalking two human species".
Wexler collaborated with Waldo Salt on the screenplay for Serpico (1973), directed by Sidney Lumet and based on Peter Maas's best-selling biography of a New York cop who bravely fought corruption within his unit. Al Pacino played the real-life policeman who refused to join in the bribe-taking that was rife in the force and risked his life to expose not only his corrupt colleagues but many of their superiors, an action which had resulted in a 1970 hearing that rocked the New York Police Department.
The film's screenplay was praised for not only providing a thrilling story, but also vividly conveying the off-beat personality of the bead- wearing, ballet-loving hero. "Norman Wexler is responsible for most of the hip humour," wrote Pauline Kael in the New Yorker. "He writes virulent low-life dialogue with a demented lift."
Mandingo (1975), scripted by Wexler for the director Richard Fleischer, was equally successful at the box office though loathed by critics. Based on a best-seller by Kyle Onstott, it was a steamily melodramatic account of slavery, sex and sadism in the old South, and the following year Wexler adapted a similar Onstott novel, Drum, though this time the public agreed with the critics and rejected the luridly sensational result - the director Burt Kennedy left the project midway and it was completed by Steve Carver.
Wexler next wrote his biggest film success, Saturday Night Fever (1977), adapting Nik Cohn's magazine piece "Tribal Rites of the New Saturday Night", the story of Tony Manero, a clerk in a Brooklyn paint store who escapes from his humdrum existence when, on Saturday nights, he transforms himself into a sleek, pomaded stud and displays his sensational skills as a disco dancer. (In one of the film's funniest moments, Tony, played by John Travolta, shouts at his father, "You hit my hair!")
With John Badham's fluid direction, the star-making performance by Travolta, an infectious score by the Bee Gees, and its pithy script (though the strong street language employed by Wexler to impart realism prompted the studio to construct an "alternate" version), the film became one of Paramount's top-grossing films of all time.
After this highspot, Wexler's career faltered. He was one of four writers who worked on the shoddy adaptation of Bob Randall's thriller The Fan (1981), starring Lauren Bacall as a Broadway star stalked by a psychotic admirer, and Wexler's own mental problems resulted in his being diagnosed as manic depressive. When in 1983 John Travolta asked him to write Staying Alive, a sequel to Saturday Night Fever, Wexler clashed disastrously with the film's director, Sylvester Stallone, who put Travolta through a course of body-building and drastically revised Wexler's screenplay, with a result described by Wexler as "vacuous, impoverished, crass and crude".
His last film, Raw Deal (1986), on which he collaborated with Gary Devore, was an undistinguished action movie for Arnold Schwarzenegger, but Wexler continued to write for the theatre and in 1996 his last play, a comedy called Forgive Me, Forgive Me Not, was produced at a theatre in Los Angeles.
Norman Wexler, actor: born Detroit, Michigan 1926; (two daughters); died Washington DC 23 August 1999.