Douglas "Clay" Cook is an American songwriter, producer, and musician who is best known as a member of the Zac Brown Band. After dropping out of college, he and classmate John Mayer formed the band Lo-Fi Masters. Cook co-wrote several songs with Mayer that appear on Mayer's first two releases, Inside Wants Out and Room for Squares, including "No Such Thing", "Comfortable", "Man on the Side" and "Neon". Cook was also a member of The Marshall Tucker Band and Y-O-U.