Don Williams, who partnered with Andy Williams and their brothers, Dick and Bob, in a singing foursome that performed on the radio, in the movies and with Bing Crosby and Kay Thompson, has died. He was 100.

Williams died Friday of natural causes at his home in Branson, Missouri, his wife, Jeanne, told The Hollywood Reporter.

Born on Oct. 9, 1922, Don was the second oldest of the Wall Lake, Iowa-bred quartet. He and his brothers would work mornings on their own live radio show in Des Moines, Iowa, and then head off to school.

Doris Day knew them since they were kids. “Often I would go over to their house, and we would sing together,” she recalled after Andy Williams’ death in September 2012. “They asked me to join their group, but my vocal coach thought I should be out on my own.”

The boys also performed on stations in Chicago and Cincinnati before they came to Los Angeles and backed up Crosby on his 1944 hit “Swinging on a Star.” Later, they teamed with Thompson to form a popular nightclub act.

Thompson, who headed the vocal department at MGM, put the brothers in the studio choir, and they worked on films including Anchors Aweigh (1945), Ziegfeld Follies (1945), The Harvey Girls (1946) and Good News (1947).

They also appeared in the musicals Janie (1944), Kansas City Kitty (1944), Something in the Wind (1947) and Ladies’ Man (1947).

Without his brothers, Don appeared on a 1956 episode of Playhouse 90 and headlined at the Tropicana hotel soon after it opened in Las Vegas in 1957. He also sang in commercials, on The Tonight Show and on programs hosted by Eddie Fisher and Nat King Cole.

Later, he became an agent and manager, with his clients including Mary Tyler Moore and singers Ray Stevens and Roger Miller.

During World War II, he served with the U.S. Merchant Marine with Dick, and both were radio operators on the same tanker.

Don Williams County Park, a recreation area in Boone County, Iowa, is named for him. 

Andy Williams, known for his easy-listening hits “Moon River,” “Days of Wine and Roses” and “Where Do I Begin?” and for his long-running TV variety show, was born in 1927 as the youngest of the boys. He died at age 84.

Bob Williams, born in 1918 as the oldest, died in September 2003 at age 85. And Dick, born in 1926, died in May 2018 at age 91.

The four reunited often for Andy Williams’ Christmas specials.

In addition to his wife — they were together for 41 years — Don’s survivors include his twin sons, David and Andy, and a grandson, Harrison. His sons recorded as the Williams Brothers, too, with their songs including “What’s Your Name” and “Can’t Cry Hard Enough.”