William Harlan Haas (born May 24, 1982) is an American professional golfer who plays on the PGA Tour and won the 2011 FedEx Cup.

He was the third member of his family to play golf at Wake Forest University in Winston-Salem, North Carolina, following his father, Jay and uncle, Jerry.

He started to turn his form around during the fall series and recorded his best finish of the year at the Viking Classic with a tie for third place.

At the start of the 2010 season Haas won his first PGA Tour title at the Bob Hope Classic in La Quinta, California.

A week prior to the event, Haas received advice from his father, Jay, and great-uncle Bob Goalby about his foot positioning during his swing.

In the fall he won his second PGA Tour title of 2010 and of his career, in October at the Viking Classic, winning by three strokes over Michael Allen.

In 2011 Haas won the season-ending Tour Championship at East Lake Golf Club, defeating Hunter Mahan in a sudden death playoff at the third extra hole.

Haas won for the fourth time on the PGA Tour in February 2012 at the Northern Trust Open at Riviera Country Club.

Haas squirted his drive out to the left to leave a tricky pitch, while Mickelson found the rough and Bradley the bunker on the right.

[6] In June 2013 Haas claimed his fifth PGA Tour title with a win at the AT&T National at Congressional Country Club.

Haas is now one of four players who have won PGA Tour events in each of the last four seasons, joining Dustin Johnson, Phil Mickelson and Justin Rose.

Haas and his father won the CVS Caremark Charity Classic in 2004, an unofficial PGA Tour event.

On February 13, 2018, Haas was involved in an automobile crash in Pacific Palisades, California in which the driver, Mark Gibello, was pronounced dead.