Jack McMillan

Jack McMillan (born 14 January 2000) is a swimmer from Belfast, Northern Ireland, who competed for Ireland in the men's 4 × 200 metre freestyle relay at the 2020 Summer Olympics and in the same event for Great Britain at the 2024 Summer Olympics. McMillan won gold in the latter event as a heat swimmer. In 2025 he won his first major international individual title, taking gold in the 400 metre freestyle at the 2025 European Short Course Swimming Championships in Lublin.

Biography McMillan swam in the heats of the 4 × 200 metre freestyle relay and although he was swapped out of the final for Duncan Scott, McMillan was awarded a gold medal as a heat swimmer when the British team won the final. In doing so he became only the second Northern Irish swimmer ever to win an Olympic gold medal in 128 years; the first had been his friend and former Team Ireland teammate Daniel Wiffen, in the same pool some 20 minutes earlier in the 800 metres freestyle.

In 2025, McMillan finished third behind James Guy in the 400 metres freestyle title at the 2025 Aquatics GB Swimming Championships and earned selection for the 2025 World Aquatics Championships in Singapore. Subsequently at the World Championships, he won the gold medal as part of the 4x200 metres freestyle team, alongside Matt Richards, James Guy, and Duncan Scott.