Robert Culp, who teamed with Bill Cosby as a secret agent in the hit 1960s television series “I Spy” and starred as one of the sexually adventurous title characters in the 1969 film “Bob & Carol & Ted & Alice,” died on Wednesday in Los Angeles. He was 79.

Mr. Culp, in love beads, in “Bob & Carol & Ted & Alice” (1969), with Elliott Gould, far left, Natalie Wood and Dyan Cannon. His agent, Hillard Elkins, said that Mr. Culp apparently died of a heart attack after collapsing outside his home.

Later in his career Mr. Culp had a recurring role as Ray Romano’s father-in-law in the sitcom “Everybody Loves Raymond,” but he may be best remembered for his role in NBC’s “I Spy” as part of an easygoing, wisecracking interracial team that was a first for network television and the inspiration for later black and white buddy films.

Secret agents and international intrigue in exotic locations loomed large on the big and small screens in the mid-1960s after the runaway success of the James Bond films. “I Spy,” which ran from 1965 to 1968, presented viewers with a couple of new twists on the formula.

Kelly Robinson, played by Mr. Culp, posed as a dissolute, globe-trotting tennis bum accompanied by his trainer, Alexander Scott, played by Mr. Cosby. Traveling from one tournament to another in glamorous settings, they carried out dangerous assignments in their real roles as agents for the Pentagon.

Blending comedy and drama, “I Spy” clicked with television audiences and established Mr. Culp as a suave leading man. After the series ended he took a starring role with Natalie Wood, Elliott Gould and Dyan Cannon in Paul Mazursky’s “Bob & Carol & Ted & Alice,” playing a documentary filmmaker keen to test emotional and sexual limits after attending a group therapy session.

Later he played the F.B.I. agent Bill Maxwell in the television series “The Greatest American Hero,” which ran from 1981 to 1983.

Robert Martin Culp was born on Aug. 16, 1930, in Oakland, Calif., and attended high school in Berkeley. He attended the College of the Pacific in Stockton, Calif.; Washington University in St Louis; San Francisco State College; and the drama school of the University of Washington, though he never earned a degree.

His first starring role in television came in 1957 with the CBS series “Trackdown,” a spinoff of “Zane Grey Theater.” As Hoby Gilman, a Texas Ranger, he hunted down criminals all over the state.

When “Trackdown” ended in 1959, Mr. Culp appeared in numerous television series, including “The Man From U.N.C.L.E.,” “Bonanza,” “The Rifleman” and “The Outer Limits” before teaming up with Mr. Cosby. Mr. Culp wrote the scripts for seven episodes of “I Spy,” and was nominated for an Emmy for all three years the show was in production. Each year, he lost to Mr. Cosby.

There were no hard feelings. He reunited with Mr. Cosby in 1972 on the film “Hickey & Boggs,” a fast-paced comedy about a couple of seedy private-eyes. The film was Mr. Culp’s directorial debut. He later appeared opposite Mr. Cosby in a 1987 episode of “The Cosby Show,” playing Scott Kelly, an old friend of Dr. Cliff Huxtable’s, and, once again as Kelly Robinson, in a 1999 episode of “Cosby” that included a dream sequence of “I Spy.” They had also reunited in the television movie “I Spy Returns” in 1994.

In other films Mr. Culp played John F. Kennedy’s best friend in “PT 109” (1963), Wild Bill Hickok in “The Raiders” (1963), Jane Fonda’s fiancé in “Sunday in New York” (1963), and the president of the United States in “The Pelican Brief” (1993).

Mr. Culp was married five times. He is survived by his daughters, Samantha, who lives in China, and Rachel, of San Francisco; and his sons, Joseph, Joshua and Jason, all of Los Angeles.