Leonard Earl "Len" Mattiace (born October 15, 1967) is an American professional golfer on the PGA Tour.
Mattiace was born in Mineola, New York. He attended Nease High School in Ponte Vedra Beach, Florida. He graduated from Wake Forest University in 1990 with a degree in Sociology. While at Wake Forest, he played on the team that won the NCAA Division I Golf Championship in 1986. He turned pro later in 1990.
Mattiace first gained notoriety when he surged into contention in the final round of the 1998 Players Championship. Trailing by one shot going into the par-3 17th hole, he hit his tee shot into the water, his third shot into a bunker, and his fourth shot into the water. He ended up with a quintuple-bogey 8 on the hole and finished in a tie for fifth, just four strokes behind the eventual winner Justin Leonard.