By Tom Gliatto
April 12, 2010 12:00 PM

Robert Culp was one of the best TV partners you could ask for. In 1965 he starred in I Spy, a breezy espionage caper about two agents using tennis as a cover. In a revolutionary casting coup, he was paired with the not yet hugely famous comic Bill Cosby, making them the first black-white leading costars in TV history. “We were an integrated team,” says Cosby, who also recalls that Culp showed him the acting ropes. “He had to teach me how to open a door properly.” And when Cosby won the first of three Emmys for the part-Culp never won-“Bob said, ‘I’m proud of you.'”

The 79-year-old Culp-married five times and the father of five-died March 24, reportedly after collapsing while walking near his L.A. home. “It’s a terrible shock,” says William Katt, who teamed up with Culp for The Greatest American Hero, the cult ’80s series in which he played a reluctant action hero to Culp’s gnarled FBI agent. “He was in good spirits, in good health.”

Good spirits seem to have been the norm for Culp. He had “this cool, hipster exterior,” says actress Patricia Heaton. When he’d arrive on the Everybody Loves Raymond set for his recurring role as her father, “he wore this Playboy Mansion letter jacket, like a varsity jacket!” Culp was, in fact, a fixture at the Playboy Mansion. He even coined its informal motto, says best pal Hugh Hefner: “Gentlemen, gentlemen, be of good cheer, for they are out there, and we are in here!”

But Culp also had a serious side, notably campaigning for civil rights. “He would hook into something that spoke to his heart,” says his son, actor Joseph Culp, 47. “He had a strong sense of what’s right.”

Culp was a constant in a changeable town. Each time they’d reunite, says Cosby, “even if it was after five years, it was like he’d just gone across the street for a loaf of bread.”