Robert Culp: Actor who played the secret agent partner of Bill Cosby in 'I Spy'

The slick television series I Spy, a 1960s espionage drama with deft touches of comedy, brought Robert Culp international fame.

As the secret agent Kelly Robinson he jetted around the world under cover as a tennis player on the international circuit.

Bill Cosby, as his spy partner Alexander Scott, was the sportsman's "coach". He became the first black actor in a regular starring role on American television.

"We have a rapport never seen on a screen before," Culp claimed of the partnership when the programme was launched. "It's a kind of Clark Gable-Spencer Tracy relationship. We're an inseparable team, a kind of Damon and Pythias. Bill and I together form what you will root for in the series."

The hip banter and camaraderie between Culp and Cosby certainly did much to attract viewers, as did the location filming across Europe and in countries such as Japan and Morocco – making it television's response to the James Bond films. But I Spy (1965-68) was gadget-free and concentrated on the ugly, realistic side of the espionage business. Humour came with the running scenario of the two agents being locked in a room and devising an ingenious scheme to escape – once creating an explosive out of chemical fertiliser and dry ice.

For Culp, taking the role of a tennis player was no stretch. He was proficient at the sport and appeared in many celebrity tournaments. Unusually at the time, he was a star who wrote some of the programme's scripts, too.

Unfortunately for him, much of the spotlight fell on Cosby, who won three consecutive Emmy Awards as best actor, beating his fellow star, who was nominated each time. But Culp insisted that there was no jealousy, adding: "I was the proudest man around." Indeed, the actors' on-screen friendship carried over off-screen. They were both civil rights activists who, after Martin Luther King's assassination, joined striking workers he had been organising in Memphis, Tennessee.

The pair reprised their screen roles in the 1994 television film I Spy Returns and, five years later, Culp turned up as Kelly Robinson in a dream sequence in an episode of the sitcom Cosby. In the intervening years, Cosby had become one the world's biggest television stars. Culp's own fortunes were mixed, but he had another success in the United States as the FBI agent Bill Maxwell, alongside William Katt as a teacher with superhuman abilities received from aliens, in the sci-fi series The Greatest American Hero (1981-83).

Culp will also be remembered as Bob, half of one of the wife-swapping couples – with Natalie Wood, Elliott Gould and Dyan Cannon – in the Swinging Sixties film comedy Bob & Carol & Ted & Alice (1969). "Robert Culp is the essence of the sagging, dissipated early-middle-age swinger," lauded the critic Roger Ebert.

Born in California in 1930, the son of a lawyer, Culp had ambitions to be an illustrator and animator until acting in community theatre at the age of 14 made him thrill to the reaction of an audience. Nevertheless, he excelled in sports such as pole vaulting, hurdles and the high jump, and won an athletics scholarship to the University of Washington, where he also had the chance to act. He switched to San Francisco State College but left without gaining a degree and moved to New York, where he studied acting at the Herbert Berghof Studio.

Culp spent a year working in a bank before his break came in the title role of He Who Gets Slapped (Actors' Playhouse, 1956), which won him an Obie Award as best actor off-Broadway. He was soon appearing on Broadway as Ivan Gorodoulin in Diary of a Scoundrel (Phoenix Theatre, 1956) and Pete in A Clearing in the Woods (Belasco Theatre, 1957).

Television offers were also forthcoming and Culp acted in many small-screen plays before landing the starring role of the Texas Ranger Hoby Gilman, on the trail of law-breakers in the Old West and noted for his "hip-diddy" walk, in Trackdown (1957-59). After a string of one-off character roles on television, he reprised that cool and hip persona when he was cast as Kelly Robinson in I Spy. By then, he already had some experience of writing, contributing scripts to Trackdown and The Rifleman (1962), the Western series starring Chuck Connors.

Culp's film career was limited, although he acted John F. Kennedy's best friend in PT 109 (1963), Jane Fonda's fiance in Sunday in New York (1963), "Wild Bill" Hickok in The Raiders (1963), the gunslinger Thomas Luther Price, alongside Raquel Welch, in Hannie Caulder (1971) and the American President in The Pelican Brief (1993).

He was reunited with Cosby as two over-the-hill private eyes in the film comedy Hickey & Boggs (1972), which Culp also directed, and he appeared in a 1987 episode of The Cosby Show as Scott Kelly, an old friend of Cosby's character, Dr Cliff Huxtable.

Culp was reported to have turned down the role of Napoleon Solo in the 1960s spy series The Man from U.N.C.L.E., which eventually went to Robert Vaughn. Later, in 1980, he was mentioned by Dallas producers as a possible replacement for Larry Hagman as J.R. Ewing when the actor demanded a massive pay rise, but they never approached Culp and eventually stuck with their original star.

In between many television films and episodes of popular series, Culp took the recurring role of Warren, father-in-law of Ray Barone (Ray Romano), in the sitcom Everybody Loves Raymond (1996-2004). The five-times-married actor also directed episodes of I Spy and The Greatest American Hero. His third marriage, from 1967 to 1970, was to the Eurasian actress France Nuyen, whom he met when she appeared in I Spy.

Robert Martin Culp, actor, writer and director: born Oakland, California 16 August 1930; married 1951 Elayne Carroll (marriage dissolved 1956), 1957 Nancy Ashe (marriage dissolved 1966; three sons, one daughter), 1967 France Nuyen (marriage dissolved 1970), 1971 Sheila Sullivan (marriage dissolved 1976), 1981 Candace Faulkner (marriage dissolved; one daughter); died Los Angeles 24 March 2010.