Answer: Ben Ainslie
The Danish Paul Elvström (1928-2016) was the first sailor with four golden medals (1948, 1952, 1956 and 1960), but Ben Ainslie (born 1977) was the first to win one silver and four gold medals. Two Brazilians have also won five medals, but only twice the gold medal: Robert Scheidt (born 1973) won twice gold, twice silver and once bronze between 1996 and 2012; and Torben Grael won two gold, one silver and two bronze medals between 1984 and 2004.
Ben Ainslie started his Olympic career in the Laser class in 1996 (Atlanta). Out of 56 competitors, Scheidt won and Ainslie was second. Third was the Norwegian Peter Moberg.
In 2000 (Sydney) Ainslie and Scheidt were the favourites for the Laser class once again, out of 43 competitors. Ainslie won before Scheidt, and the bronze was for the Australian Michael Blackburn. Scheidt entered two protests against Ainslie about having hindered him in the final race, but to no avail. In 2004 (Athens) Ainslie moved on to the heavier Finn class. Out of 26 competitors, Ainslie finished first, followed by the Spaniard Rafael Trujillo and the Pole Mateusz Kusznierewicz.
In 2008 (Beijing) Ainslie was once more the favourite in the Finn class, with 26 competitors. Ainslie took the gold before the American Zach Railey and the French Guillaume Florent. In 2012 (London) Ainslie and the Danish Jonas Hogh-Christensen were fierce contenders for the gold medal. In the regular races (with all 24 competitors) Hogh-Christensen held a very small advantage over Ainslie, but in the final medal race Ainslie closed the gap. Because the medal race was decisive in case of a tie, Ainslie won the gold and Hogh-Christensen the silver. The French Jonathan Lobert just preceded the Dutch Pieter-Jan Postma for the bronze.
Rodney Pattisson (born 1943) won two gold medals in 1968 and 1972, and added a silver medal in 1976. Sarah Webb (born 1977) and Sarah Ayton (born 1980) together won gold in 2004 and 2008 in the Yngling class, with the third member on their team being Shirley Robertson in 2004 and Pippa Wilson in 2008.