In the history of the four modern men's major championships in golf -- the Masters, US Open, British Open Championship and PGA Championship -- the lowest 72-hole total belongs to two players.
Henrik Stenson did it first when he won the 2016 British Open Championship with a total of 264, including a final-round 63 to hold off Phil Mickelson at Royal Troon. Two years later, Brooks Koepka shot 16-under 264 to win the 2018 PGA Championship at Bellerive Country Club in St. Louis.
With that performance, Stenson also took a share of the 72-hole major championship scoring record in relationship to par. Two players have posted a 20-under total at a major championship, with Stenson doing so at Troon on a par-71 course and Jason Day doing it at the 2015 PGA Championship on a par-72 Whistling Straits (Straits Course) in Wisconsin.
Of course, most golf fans also know the lowest 18-hole score ever recorded in a major championship. It's a fairly recent record. Branden Grace shot 8-under 62 in the third round of the 2017 British Open Championship at Royal Birkdale to become the first and only player in major championship history to shoot 62. There had previously been 32 rounds of 63 in major championships, with Tommy Fleetwood adding another 63 in the final round of the 2018 US Open at Shinnecock Hills.
The other significant scoring records in men's major championships are a little muddier, but there are 36-hole and 54-hole scoring records acorss the four major championships.
The lowest 36-hole total in any major championship is 130, shot by four different players in three majors. Jordan Spieth shot 130, going 64-66 in the 2015 Masters. Martin Kaymer shot a pair of 65s to open at the 2014 US Open at Pinehurst No. 2 before winning his second major championship. In the British Open Championship, Nick Faldo went 66-64 en route to winning in 1992. Brandt Snedeker also opened 66-64 in 2012 at Royal Lytham and St. Annes. He finished tied for third that week, behind winner Ernie Els. Gary Woodland shot 130 by going 64-66 in 2018 at Bellerive Country Club in St. Louis.
The lowest 54-hole total in any major championship belongs to David Toms, with his first three rounds in 196 at Atlanta Athletic Club in the 2001 PGA Championship. Before Stenson's win at Royal Troon, Toms owned the low 72-hole total in major championship history.