William Michael Heinen, Jr. (born January 17, 1967) is an American professional golfer who has played on the PGA Tour and the Nationwide Tour.

Heinen was born in Rayne, Louisiana and raised in Fenton, Louisiana. He attended the University of Louisiana at Lafayette from 1985-1989, and was a two-time All-American member of the golf team. He turned pro in 1989.

Throughout his career, Heinen has split his playing time in relatively equal amounts between the PGA Tour and the Nationwide Tour. In 1994, he won the Shell Houston Open in just his 10th start on the PGA Tour. He lives in Lake Charles, Louisiana with his wife and three children.