Ian Williams (born August 31, 1970) is an American guitarist/keyboardist known for his work in the math rock bands Don Caballero and Battles, as well as in the improvisational band Storm & Stress. Following the break-up of Don Cab in 2000 (and the subsequent hiatus of Storm & Stress), Ian took a two-year break from group projects to perform alone, and in 2002 became a founding member of Battles, with whom he continues to play to this day.
Ian is known for his distinct finger-tapping style, allowing him to use one hand for guitar and one hand for keyboards when performing live.