William R. Flagg (born 1934) was an American country and rockabilly singer from Waterville, Maine. Flagg was the first musician known to use the term ârockabillyâ to describe his style. He began his career as a radio performer called âThe Lone Pine Cowboyâ and played bluegrass before transitioning to rockabilly in 1954 with John Sligar. In 1956, Flagg signed with Tetra Records and formed the band The Rockabillies. The group recorded the singles âGo Cat Goâ and âGuitar Rockâ, which did not appear on the Billboard charts. In 1958, Flagg moved to MGM Records for his final single before leaving the industry to manage his family's business. Following a twenty-seven-year hiatus, he returned to music with the bluegrass ensemble Hobo Bill and the Last Ride. His discography included the album Then and Now. Bill Flagg died in Southbridge, Massachusetts, on November 19, 2024.