Usain Bolt from Jamaica.
Ian Thorpe.
Men: Michael Johnson, United States Women: Cathy Freeman, Australia
Cathy Freeman won 1 gold medal at the Olympic Games (400 meter dash in 2000), 2 gold medals at the World Championships (400 meter dash in 1997 and 1999), and 4 gold medals at the Commonwealth Games (4x100 meter relay in 1990, 200 meter dash and 400 meter dash in 1994, and 4x400 meter relay in 2002).
Ian Thorpe with 5. Thorpe's gold came in 400 meter freestyle in 2000 and 2004, 200 meter freestyle in 2004, 4x100 meter freestyle in 2000, and 4x200 meter freestyle in 2000.
Brooke Bennett for the women and Ian Thorpe for the men. Ian was Australian and Brooke was American. Both competed in the 400 meter freestyle if that is the type of 400m you meant.
Men: Michael Johnson Women: Cathy Freeman
Yes. She won silver in the 400 meter run at the 1996 Games in Atlanta and gold in the 400 meter run at the 2000 Games in Sydney.
That is swimmer Ian Thorpe in the 400 meter freestyle. Thorpe won gold in the 400 meter freestyle at the 2000 and 2004 Summer Games.
Men: Michael Johnson Women: Cathy Freeman
Cathy Freeman participated in three Olympics (1992 in Barcelona, 1996 in Atlanta, 2000 in Sydney). She won two medals, a silver medal in the 400 meter dash in 1996 and a gold medal in the 400 meter dash in 2000.
Cathy Freeman was a short distance runner who competed, at various times in her career, in the 400 meter run, 200 meter run, 4x400 meter relay, and 4x100 meter relay. She is most well known for her performances in the 400 meter run where she won a gold medal at the 2000 Summer Olympics in Sydney and gold medals in the Commonwealth Games and World Championships.
19 years old. Swimmer Rebecca Adlington (born February 17, 1989) won gold in the women's 400 meter freestyle and women's 800 meter freestyle at the 2008 Games.