Bill Elgart or Billy Elgart (born November 9, 1942, Cambridge, Massachusetts) is an expatriate American jazz drummer. He is related to Les and Larry Elgart. Elgart was born in Chelsea, Massachusetts. He studied at the Berklee College of Music and was a student of Alan Dawson. In the 1960s he played with Carla Bley, Paul Bley, Marion Brown, Sam Rivers, Lowell Davidson, Mark Levinson, Roswell Rudd, John Tchicai, Jack Walrath and Glenn Ferris. In 1968 he made his recording debut on Mr. Joy, with Paul Bley and Gary Peacock.