#6 Rod Laver
Rod Laver beat compatriot Tony Roche in the US Open finals of 1969 to become the sixth oldest person to have won a Grand Slam title. He was 31 years and 1 month old at that time.
Laver defeated Roche in four sets: 7-9, 6-1, 6-2, 6-2.
#5 Arthur Ashe (United States of America)
Arthur Ashe beat top-ranked Jimmy Connors in the 1975 Wimbledon finals. Ashe was 31 years, 11 months and 25 days old at the time of the match, making him the fifth oldest Slam winner in the Open Era.
The score line read: 6-1, 6-1, 5-7, 6-4.
#4 Andre Agassi (United States of America)
In 2003, Andre Agassi beat 31st-ranked Rainer Schuttler in the Australian Open final to earn another place in the record books as one of the oldest players to have won a Major. He was aged 32 years, 8 months and 28 days at the time.
Agassi won the match in straight sets 6-2, 6-2, 6-1.