The Los Angeles Times said the "I Spy" and "Everybody Loves Raymond" star had been taking a walk when he fell and hit his head. He was discovered a short time later by a passing jogger, who called 911.
Paramedics transported Culp to Queen of Angels hospital where he was pronounced dead.
Police told the Times Culp's death appears accidental and said there are no signs of foul play.
Culp -- who co-starred with Dyan Cannon, Elliott Gould and Natalie Wood in the film "Bob & Carol & Ted & Alice" -- was nominated for four Emmys for "I Spy," three for acting and one for writing.
He also appeared opposite Julia Roberts and Denzel Washington in "The Pelican Brief," and appeared on the TV shows "The Man From U.N.C.L.E.," "Columbo" and "The Greatest American Hero."
Born Aug. 16, 1930, in Oakland, Calif., Culp broke through in Hollywood in 1957 as the star of the TV Wester "Trackdown," in which he played Texas Ranger Hoby Gilman.
In "I Spy," he and Bill Cosby co-starred as a team of U.S. spies who traveled the world undercover, posing as a tennis pro and his manager.