Who was the first person to win gold medals in the same event in both the Winter and Summer Olympics?

Gillis Emanuel Grafström (7 June 1893 – 14 April 1938) was a Swedish figure skater. He was born in Stockholm, Sweden. He won three successive Olympic gold medals in Men's Figure Skating (1920, 1924, 1928) as well as an Olympic silver medal in the same event in 1932, and three World Championships (1922, 1924, 1929). He and Eddie Eagan are the only athletes to have won a gold medal at both the Summer and Winter Olympic Games.

Gillis Grafström won gold in both the Summer and Winter Olympic Games but it was in the same event. That is because in 1920, prior to the Winter Olympics, figure skating was part of the Summer Olympics. Grafstrom is one of the few athletes who have competed in both the Summer and Winter Olympic games and won medals in both.