William James O'Brien (born October 23, 1969) is an American football coach who is currently the offensive coordinator and quarterbacks coach at the University of Alabama. O'Brien previously served as the head coach of the Houston Texans of the National Football League (NFL) from 2014 to 2020 and at Pennsylvania State University from 2012 to 2013. He also served as the general manager of the Texans in 2020.