Friends and costars recall the actor's sophistication and gentleness

The life and career of beloved comic actor Don Knotts are paid tribute in PEOPLE’s latest issue.

Perhaps not surprisingly, Knotts’s final hours included his costar on the classic ’60s sitcom The Andy Griffith Show, Andy Griffith – who was at his old pal’s bedside on Feb. 24, just a few hours before Knotts succumbed at 81 to complications from lung cancer in an L.A. hospital.

“I told him I loved him and I held his hand,” says Griffith, 79. “I said, ‘You gotta breathe, Jess!’ Jesse was his (real) first name. ‘You gotta whip this thing.'” Though Knotts was unconscious, “his chest heaved several times, and I believe he heard my voice.”

So deep was the friendship between the two men, “They would talk on the phone for hours and share the deepest confidences,” Knotts’s third wife, Francey Yarborough, tells PEOPLE. Diagnosed last November, Knotts, who’d quit smoking decades ago, “was upbeat and getting chemo,” she also says. “But he didn’t even tell his own children. He figured he’d beat it and go on with his life.”

The real Don Knotts was nothing like blustery Barney, says Griffith. “He was modest, he was humble and he was very bright.” Adds director Ron Howard, who played Andy’s son Opie: “He was just one of those truly kind people, very unassuming and very respectful.”

But there was another side to Knotts. “Dad was kind of wild,” says Karen Knotts, his actress daughter by first wife Kathryn Metz, with whom he also had a son, Thomas, now an electrical engineer. “He was really quite a ladies’ man, especially between marriages.”

Says Joyce DeWitt, best known as Janet Wood on Three’s Company, on which Knotts played landlord Ralph Furley: “He was also a gracious, kind, lovely, clever, interesting and rather sophisticated man, and he was suave in his own elegant way. He was our darling Don.”

Still, insists pal Tim Conway, the Carol Burnett Show veteran who performed with him on The Steve Allen Show and teamed with him in five movies from 1975 to 1980: “He was Barney Fife, there’s no question about it. He had the front of being a very secure guy until things started to crumble around him. He’s the confident guy who has no business being confident. … He left us with a wonderful, gentle character who can never be duplicated.”