How many times did Tom Watson won the British Open?

15, 5 Masters (1997, 2000, 2001, 2005 and 2009) 3 US Opens (2000, 2002 and 2008) 3 British Opens (2000, 2005 and 2006) and 4 USPGA Championships (1999, 2000, 2006 and 2007).

2nd most all-time after Jack Nicklaus who has 18.