William Fred Mayfair (born August 6, 1966) is an American professional golfer who plays on the PGA Tour .
Mayfair was born in Phoenix, Arizona. Before his fifteenth birthday, he had won a number of junior golf tournaments. In 1981, he was on the cover of Boys' Life magazine as "golf's junior hotshot". He attended Arizona State University and was a member of the golf team. He won the 1986 U.S. Amateur Public Links and the 1987 U.S. Amateur Championship, defeating University of Tennessee graduate Eric Rebmann 4&3. He won the 1987 Haskins Award for the nation's top collegiate golfer.
Mayfair turned professional in 1988 and has won five events on the PGA Tour, including the 1995 Tour Championship. He has featured in the top 50 of the Official World Golf Rankings. He holds the distinction of being the only player to ever beat Tiger Woods in a playoff on the PGA Tour (1998 Nissan Open).