William Henry Hanzlik (born December 6, 1957) is an American former professional basketball player and coach.

Coach Doug Moe often assigned Hanzlik to the opposing team's toughest player to guard, regardless of position, even once defending 7'4" center Ralph Sampson, with success.

In 1997, Hanzlik (then an assistant with Atlanta) was tabbed to replace Dick Motta as head coach of the Denver Nuggets.

To date, Hanzlik owns the worst full-season record for a rookie coach in NBA history.

In 1986, he and Ray Baker formed the Gold Crown Foundation, a non-profit that operates year-round sports programs for area youths.