Duncan William MacNaughton Scott (born 6 May 1997) is a British swimmer representing Great Britain at the FINA World Aquatics Championships and the Olympic Games, and Scotland at the Commonwealth Games. An all-rounder in the pool, Scott has swum internationally in 100 and 200 metres freestyle and butterfly, and 200 metres individual medley. He has won two golds at the World Championships in 4 x 200 metre freestyle relay, a gold in the 4 x 100 metre medley relay, as well as silvers at the World Championships and Olympics in freestyle and medley relay. Individually, Scott was the 100 metre freestyle champion at the 2015 European Games and 2018 Commonwealth Games, and the 200 metre freestyle champion at the same European Games and the 2018 European Aquatics Championships.
Winning three gold medals in the (100 m and 200 m freestyle, and 4 × 100 m freestyle relay) at the 2015 European Games, he was the most successful British athlete at the Games. A month later, he formed part of the Great Britain squad that won the gold medal at the 2015 World Aquatics Championships in the men's 4 x 200 metre freestyle relay as the 4th leg swimmer in the heat. In 2016, he was a member of the Great Britain team that won silver in the final of the same event at the Olympic Games as well as the men's 4 x 100 metre medley relay. The same team also won the 4 x 100 metre medley relay silver in the 2017 World Championships. A noted relay swimmer, Scott broke the individual British 200 metre freestyle record leading off in the men's 4 x 200 metre relay, before anchoring the team that won gold in 4 x 100 metre medley relay at the 2019 World Championships.