William Fitzsimmons is an American singer-songwriter based in Nashville, Tennessee. His music has been featured on ABC's Brothers & Sisters and the Grey's Anatomy spin-off Private Practice, MTV's Life of Ryan and Teen Wolf, the CW's One Tree Hill, CBS's Blue Bloods, ABC Family's Greek, Lifetime's Army Wives, and USA Network's Burn Notice. As of 2024, he has released nine studio albums, one EP, one live album, one remix album, and two cover albums.