Viktor Ahn, Russia
Results: four events, three gold medals, one bronze medal
Viktor Ahn, or Ahn Hyun-soo, was one of South Korea's most successful short-track speedskaters, but his conflict with the country's federation dated back to 2006, when he won three golds and a bronze in Turin. After being slowed by injuries, Ahn failed to qualify for the 2010 Olympics in Vancouver and was by then virtually discarded by his team. Citing his desire to train in the best possible environment, Ahn moved to Russia in 2011 and entered the Sochi Olympics as a Russian citizen.
Ahn started off with a bronze in the 1,500 meters and then went on to sweep the gold in the 1,000 meters and 500 meters before anchoring Russia's 5,000-meter relay victory. His domination at Sochi made him the most decorated short-track skater ever, with six gold medals (the only skater to have won gold in all four events) and he tied Apolo Anton Ohno with eight medals overall. While Ahn led a Russian team that never medaled in short track in previous Olympics, South Korea's men netted exactly zero medals, by far their worst showing since the event became an Olympic sport in 1992.