His wholesome image endured one jarring interlude.
In 1976, his ex-wife, former Las Vegas showgirl Claudine Longet, shot and killed her lover, skiing champion Spider Sabich. The Rolling Stones mocked the tragedy in "Claudine," a song so pitiless that it wasn't released until decades later. Longet, who said the slaying was an accident, spent only a week in jail. Williams stood by her. He escorted her to the courthouse, testified on her behalf and provided support for her and their children, Noelle, Christian and Robert.
Also in the 1970s, Williams was seen frequently in the company of Ethel Kennedy, Robert Kennedy's widow. The singer denied any romantic involvement.
He was born Howard Andrew Williams in Wall Lake, Iowa, on Dec. 3, 1927, and began performing with older brothers Dick, Bob and Don in the local Presbyterian church choir. Their father, postal worker and insurance man Jay Emerson Williams, was the choirmaster and the force behind his children's career.
When Andy was 8, Williams' father arranged for the kids to have an audition on Des Moines radio station WHO's Iowa Barn Dance. They were initially turned down but kept returning until they were finally accepted. The show attracted attention from Chicago, Cincinnati and Hollywood. Another star at WHO was a young sportscaster named Ronald Reagan, who would later praise Williams as a "national treasure."
The brothers later worked with Kay Thompson, a singer who eventually became famous for the "Eloise" children's books. She had taken a position as vocal coach at MGM studios, working with Judy Garland, June Allyson and others. After three months of training, Thompson and the Williams Brothers broke in their show at the El Rancho Room in Las Vegas, drawing rave reviews and as much as $25,000 a week.
After five years, the three older brothers, who were starting their own families, had tired of the constant travel and left to pursue other careers.
Williams initially struggled as a solo act and was so broke at one point that he resorted to eating food intended for his two dogs.
A two-year TV stint on Steve Allen's "Tonight Show" and a contract with Cadence Records turned things around. Williams later formed his own label, Barnaby Records, which released music by the Everly Brothers, Ray Stevens and Jimmy Buffett.
Williams was a lifelong Republican who once accused President Barack Obama of "following Marxist theory." But he acknowledged experimenting with LSD, opposed the Nixon administration's efforts in the 1970s to deport John Lennon and in 1968 was an energetic supporter of Robert Kennedy's presidential campaign.
When Kennedy was assassinated in Los Angeles in June 1968, just after winning the California Democratic primary, Williams sang "The Battle Hymn of the Republic" at his funeral.
"We chose that song because he used it on the campaign trail," Williams later said of Kennedy, who had been a close friend. "He had a terrible voice, but he loved to sing that song. The only way I got through singing in church that day was by saying, 'This is my job. I can't let emotion get in the way of the song.' I really concentrated on not thinking about him."
After giving up touring, he settled in Branson, with its dozens of theaters featuring live music, comedy and magic acts, and was among the first wave of national entertainers to perform there regularly.
When he arrived in 1992, the town was dominated by country music, but Williams changed that with his classy, $13 million theater in the heart of the entertainment district, where he did two shows a night, six days a week, nine months of the year. Only in recent years did he cut back to one show a night. His most popular time was Christmas.
Not everyone in Hollywood accepted his move to the Midwest. "The fact is most of my friends in LA still think I'm nuts for coming here," he told The Associated Press in 1998.
He and his second wife, the former Debbie Haas, divided their time between homes in Branson and Palm Springs, Calif., where he spent his leisure hours on the golf course when Branson's theaters were dark during the winter months following Christmas.
Retirement was not on his schedule. As he told the AP in 2001: "I'll keep going until I get to the point where I can't get out on stage."
Williams is survived by his wife and his three children.
Thomas reported from Los Angeles. AP Entertainment Writer Nekesa Mumbi Moody contributed to this report from Nashville, Tenn.