William Mack Brown (born August 27, 1951) is head coach of The University of Texas at Austin Longhorn football team.

Prior to coaching at Texas, Brown coached at Appalachian State, Tulane, and North Carolina. Brown is credited with revitalizing the Texas and North Carolina football programs. The Longhorns beat USC in the 2005 Rose Bowl, Ohio State at The Horseshoe in September 2005, and division rival Oklahoma in 1998, 1999, 2005, 2006, and 2008. The 2005 season was capped off by victories over Colorado and USC to win the Big 12 conference and national championships, respectively. In 2006 he was awarded the Paul "Bear" Bryant Award for "Coach of the Year".

Brown is one of the five highest-paid coaches in the sport. UT has announced Brown will be succeeded at Texas by his defensive coordinator, Will Muschamp, though no timetable is set for a transition. On November 27, 2008 Brown achieved his 200th career win, making him the first Texas coach to reach that mark.