William J. "Billy" Guste, Jr. (May 26, 1922 – July 25, 2013) was a New Orleans attorney, businessman and Democratic attorney general of Louisiana from 1972 to 1992. He succeeded the scandal-plagued Jack P.F. Gremillion, a fellow Democrat who had held the position since 1956. Guste received recognition for molding the office into a model of integrity and efficiency. In 1976, he helped Jimmy Carter win Louisiana and served as the first elector in the state for the Carter-Mondale slate.