William Overton Smith (September 22, 1926 – February 29, 2020) was an American clarinetist and composer. He worked extensively in modern classical music, third stream and jazz, and was perhaps best known for having played with pianist Dave Brubeck intermittently from the 1940s to the early 2000s. Smith frequently recorded jazz under the name Bill Smith, but his classical compositions are credited under the name William O. Smith.