The most decorated athlete in Olympic history, American swimmer Michael Phelps won 22 career medals before the Rio Games. Phelps was just 15 years old when he made his Olympic debut, at the 2000 Games in Sydney. Though he didn't medal in Australia, the young Phelps put the world on notice with a fifth-place finish in the 200-meter butterfly final.
Phelps would go on to win eight medals at the 2004 Athens Olympics, eight in Beijing in 2008 and six in London in 2012.
Athens 2004
Aug. 14
400-meter medley – GOLD – 4:08.