William Henry Marcus Miller Jr. (born June 14, 1959) is an American musician, songwriter, and record producer. He is best known for his work as a bassist. He has worked with trumpeter Miles Davis, pianist Herbie Hancock, singer Luther Vandross, and saxophonist David Sanborn, among others. He was the main songwriter and producer on three of Davis’ albums: Tutu (1986), Music from Siesta (1987), and Amandla (1989). His collaboration with Vandross was especially close; he co-produced and served as the arranger for most of Vandross’ albums, and he and Vandross co-wrote many of Vandross’ songs, including the hits “I Really Didn’t Mean It“, “Any Love“, “Power of Love/Love Power” and “Don’t Want to Be a Fool“. He also co-wrote the 1988 single “Da Butt” for Experience Unlimited.

William Henry Marcus Miller Jr. was born in the Brooklyn borough of New York City on June 14, 1959. He grew up in a musical family; his father, William Miller, was a church organist and choir director. Through his father, he is the cousin of jazz pianist Wynton Kelly. He became classically trained as a clarinetist and later learned to play keyboards, saxophone, and guitar.