Jack Nicklaus has won a total of 18 Majors. His first four were the 1962 US Open, the 1963 Masters, the 1963 PGA Championship and the 1965 Masters.
Tiger Woods has won a total of 15 Majors. His first four were the 1997 Masters, the 1999 PGA Championship, the 2000 US Open and the 2000 Open Championship.
Rory McIlroy to date has won a total of 4 Majors. He won the 2011 US Open, the 2012 PGA Championship, the 2014 Open Championship and the 2014 PGA Championship.