Michael Phelps comes at the top of our list as the greatest US Olympian. He's won 20 medals, 16 of which are gold and is celebrated as the greatest champion in the history of the Summer Games. But before Phelps, there was Mark Spitz, who was the first athlete to win seven gold medals in a single Olympic Games, setting world records in all seven events. Carl Lewis won the 100-meter, 200-meter, long jump and 4x100-meter relay all in one year. Lewis has 10 medals, nine of which are gold.