Wendt's family said he died peacefully in his sleep while at his Los Angeles home early on Tuesday morning.
"George was a doting family man, a well-loved friend and confidant to all of those lucky enough to have known him," the family said in a statement.
"He will be missed forever."
Despite a long career of roles on stage and on TV, it was as gentle and henpecked Norm Peterson on NBC's Cheers that he was most associated, earning six straight Emmy Award nominations for best supporting actor in a comedy series from 1984 to 1989.
The series was centred on lovable losers in a Boston bar and starred Ted Danson, Shelley Long, Rhea Perlman, Kelsey Grammer, John Ratzenberger, Kirstie Alley and Woody Harrelson.
It would spin off another mega-hit in Frasier and was nominated for an astounding 117 Emmy Awards, winning 28 of them.
Wendt, who spent six years in Chicago's renowned Second City improv troupe before sitting on a bar stool at the place where everybody knows your name, did not have high hopes when he auditioned for Cheers.
"My agent said, 'It's a small role, honey. It's one line. Actually, it's one word.' The word was 'beer'. I was having a hard time believing I was right for the role of 'the guy who looked like he wanted a beer'. So I went in, and they said, 'It's too small a role. Why don't you read this other one?' And it was a guy who never left the bar," Wendt told GQ in an oral history of Cheers.
"Cheers" premiered in 1982 and spent the first season with low ratings.
NBC president Brandon Tartikoff championed the show, and it was nominated for an Emmy for best comedy series in its first season.
Some 80 million people would tune in to watch its series finale 11 years later.
Wendt became a fan favourite in and outside the bar - his entrances were cheered with a warm "Norm!" - and his wisecracks always landed.
"How's a beer sound, Norm?" he would be asked by the bartender.
"I dunno. I usually finish them before they get a word in," he would respond.
After Cheers, Wendt starred in his own short-lived sitcom The George Wendt Show and had guest spots on TV shows such as The Ghost Whisperer, Harry's Law and Portlandia.
He was part of a brotherhood of Chicago Everymen who gathered over sausage and beers and adored "Da Bears" on Saturday Night Live. In 2023, he competed on The Masked Singer.
But he found steady work on stage: Wendt slipped on Edna Turnblad's housecoat in Broadway's Hairspray beginning in 2007, and was in the Tony Award-winning play Art in New York and London.
He starred in the national tour of 12 Angry Men and appeared in a production of David Mamet's Lakeboat. He also starred in regional productions of Death of a Salesman, The Odd Couple, Never Too Late and Funnyman.
"A, it's by far the most fun, but B, I seem to have been kicked out of television," Wendt told the Kansas City Star in 2011.
"I overstayed my welcome. But theatre suits me."
Wendt had an affinity for playing Santa Claus, donning the famous red outfit in the stage musical Elf on Broadway in 2017 as well as films and Christmas TV specials.
Born in Chicago, Wendt attended Campion High School, a Catholic boarding school in Wisconsin, and then Notre Dame, where he rarely went to class and was kicked out. He transferred to Rockhurst University in Kansas City and graduated after majoring in economics.
He found a home at Second City in both the touring company and the main stage.
"I think comedy is my long suit, for sure. My approach to comedy is usually not full-bore clownish," he told the AP.
He is survived by his wife, Second City alum Bernadette Birkett, who voiced Norm's never-seen not-so better half, Vera, on Cheers; his children, Hilary, Joe and Daniel; and his stepchildren, Joshua and Andrew.
