Forsythe, who had heart bypass surgery in 1979 and was hospitalized for colon cancer in 2006, died at his home in the Santa Barbara County town of Santa Ynez from complications of pneumonia, publicist Harlan Boll said.
Skilled at both comedy and drama, the actor began his long career on Broadway, where he stepped in for Henry Fonda in "Mister Roberts" and later originated the lead role in the hit comedy "Teahouse of the August Moon." He also appeared in many films, including Alfred Hitchcock's "The Trouble With Harry" and "Topaz."
But he was best known for three roles: Bentley Gregg, a bachelor uncle whose social life is curtailed when he must care for a young niece; the unseen Charlie, who gives three sexy young detectives their assignments in "Charlie's Angels"; and, most notably, Blake Carrington, the oil tycoon around whom life revolves in one of TV's most successful prime-time soap operas, “Dynasty,” which aired from 1981 to 1989.
The actor once described Carrington as "ruthless, powerful, cruel, selfish, kind, loving, tender, passionate." A dashing character, he inspired catfights between his vengeful ex-wife (Joan Collins) and melancholy second wife (Linda Evans) while fending off nonstop crises.
"He was one of the last true gentlemen of the acting profession," Collins said in a statement. "I enjoyed our . . . feuding, fussing and fighting as the Carringtons."
Forsythe got the role partly because he had played against his good-TV-dad image as a sadistic judge in the 1979 Norman Jewison film ". . . And Justice for All," which starred Al Pacino.
"To be seen in so unredeemable a part was a revelation to some people," Forsythe told The Times in 1980 of his portrayal of the judge.
He was born John Lincoln Freund on Jan. 29, 1918, in Penns Grove, N.J., to Samuel Freund and his wife, Blanche. When John was 6, the family moved to New York City, where his father worked on Wall Street.
A baseball player in high school and college, Forsythe attended the University of North Carolina at Chapel Hill and spent summers as a public-address announcer at Ebbets Field for the Brooklyn Dodgers.
"Even then he had this caressing, mellifluous voice . . . and drop-dead good looks that would make him a show business staple for half a century," Times sports columnist Jim Murray wrote of Forsythe in 1990.
After dropping out of college as a junior, Forsythe took roles on radio soap operas before segueing to film.
He had parts in two 1943 war-related movies, most notably "Destination Tokyo" with Cary Grant. That same year, he joined the Army Air Forces and continued his acting as Pvt. John Forsythe in Moss Hart's "Winged Victory," the Broadway play produced by the Army Air Forces.
After the war, Forsythe returned to the stage as one of the progeny in Arthur Miller's "All My Sons," directed by Elia Kazan. He also studied at the Actors Studio, where his gentlemanly clothes stood out.
Marlon "Brando and Montgomery Clift and all those were in torn T-shirts, and I had my button-down collars," Forsythe later said. "They called me the Brooks Bros. bohemian."
He toured with "Mister Roberts" and filled in for Fonda in the title role during the show's three-year Broadway run.
By then, Forsythe was dabbling in television on live dramas such as "Kraft Television Theatre" but was back on Broadway in 1953 in "The Teahouse of the August Moon." His genial performance in the long-running comedy earned comparisons to Fonda.
"It gave me a sense of worth as an actor," Forsythe later said of the role.
In the 1950s, he starred in many films, including "It Happens Every Thursday" with Loretta Young, "Everything but the Truth" with Maureen O'Hara and "The Trouble With Harry," which marked the film debut of the young Shirley MacLaine.