Isaac Willis was an American vocalist and guitarist best known for being a regular member of Frank Zappa's studio and touring bands from 1978 until the last tour in 1988. He is most recognized for his involvement in Zappa records by playing Joe in Joe's Garage, providing vocals on Tinsel Town Rebellion, You Are What You Is, and The Man from Utopia, and as the title character and narrator in Zappa's off-Broadway-styled conceptual musical Thing-Fish, as well as singing and playing on the majority of Zappa's band-oriented studio and live recordings during the 1980s.