LOS ANGELES - Robert Culp, the actor who teamed with Bill Cosby in the racially groundbreaking TV series "I Spy" and was Bob in the critically acclaimed sex comedy "Bob & Carol & Ted & Alice," died Wednesday after collapsing outside his Hollywood home, his agent said. Culp was 79.

His manager, Hillard Elkins, said the actor was on a walk when he fell. He was taken to a hospital and pronounced dead just before noon. The actor's son was told he died of a heart attack, Elkins said, though police were unsure if the fall was medically related.

Los Angeles police Lt. Robert Binder said no foul play was suspected. Binder said a jogger found Culp, who apparently fell and struck his head.

Culp had been working on writing screenplays, Elkins said.

"I Spy," which aired from 1965 to 1968, was a television milestone in more ways than one. Its combination of humor and adventure broke new ground, and it was the first integrated television show to feature a black actor in a starring role.

Culp played Kelly Robinson, a spy whose cover was that of an ace tennis player. (In real life, Culp actually was a top-notch tennis player who showed his skills in numerous celebrity tournaments.). Cosby was fellow spy Alexander Scott, whose cover was that of Culp's trainer. The pair traveled the world in the service of the U.S. government.

The series greatly advanced the careers of both actors.

Cosby, who had achieved fame as a standup comedian, proved he could act. Culp, who had played mostly heavies in movies and TV, went on to become a film star.

He followed "I Spy" with his most prestigious film role, in "Bob & Carol & Ted & Alice." The work of first-time director Paul Mazursky, who also co-wrote the screenplay, it lampooned the lifestyles of the sexual revolution of the 1960s.

Culp's first starring TV series, "Trackdown" (1957-1959) was a Western based partly on files of the Texas Rangers. In the 1980s, he starred as an FBI agent in the fantasy "The Greatest American Hero."