Michael Johnson (men) Cathy Freeman (women)
She first competed in Atlanta in 1996 and won the silver metal in 400m and then again in Sidney in 2000 when she won the gold in the same event.
In the most recent Olympics (2012), Sun Yang of China won the gold in the 400m freestyle.
She has won many times, once in the 400m at the Olympics.
Maurice Greene (USA) won the 100m at the 2000 Sydney Olympics with the time of 9.87 with -0.3m/s wind.
Only one Canadian, Donovan Bailey, has won the 100m sprint at the Olympics. Ben Johnson was the first to cross the finish line in the 100m sprint at the Seoul Olympics, but was later disqualified for steroid use.
In 2000, Ian Thorpe won the Olympic gold medal in the 400m freestyle, the 4x100m freestyle, and the 4x200m freestyle.