When director John Landis first met Don Rickles, he was just an 18-year old “go-fer, a schlepper,” on the set of war comedy “Kelly’s Heroes.” Long before Landis directed such classics as “Animal House” and “The Blues Brothers,” the young production assistant forged many friendships over the nine-month shoot in Yugoslavia.

“For me at 18, it was heaven,” says Landis of working with the likes of Rickles, Donald Sutherland, Clint Eastwood, Harry Dean Stanton, and Telly Savalas.

Flash forward more than four decades and many Rickles shows later, to 2007, when Landis is approached by Rickles’ son Larry, who died in 2011, to direct a film about his dad. “I didn’t think he was getting the respect he should,” even though he was still appearing on talkshows, Landis explains.

The legendarily hard-working comedian was hesitant at first, worrying that putting his act on TV might mean fewer people would come to his live shows. So he asked Landis to use no more than 15 minutes of performances, and “Mr. Warmth: The Don Rickles Project” became a documentary rather than a concert film. “I wanted to capture not only what he did, but who he was,” Landis says.

“His act was at least 40 percent – maybe 50 percent improvised. He’s real old school.”

When the octogenarian walks on stage in the film, “he drops 30 years,” Landis says.

“He created an atmosphere, it was really performance art, where whatever he did was funny,” says Landis, “He was one of those unique talents – he could take a room and just seize it.”

“He’s an equal opportunity slanderer, yet no one takes offense,” Landis says. As Sarah Silverman says in the film, “Everyone wants to be sh** on by Don Rickles.”

“Mr. Warmth” ended up winning Emmys both for Rickles for individual performance and for outstanding variety, music, or comedy special. “It had a very happy ending,” Landis says.

The director says the man himself was as far from his acerbic jibes as could be. “He was kind and generous and warm. This is a very sad time for me, because I loved him,” says Landis. “It’s like losing a really beloved uncle.”

Like Joan Rivers and other comics of that generation of comedians, Rickles never stopped performing. When Landis spoke to him after the comedian began heaving health problems, Landis says he wanted to get well fast, not so he would feel better, but so he could get back on the stage. Or as George Burns once told Landis, “I can’t die, I’m booked.”