Michael Phelps
The young American swimmer broke one of the most long-standing and celebrated records in sport in Beijing in August when he won eight gold medals at a single Olympiad to surpass Mark Spitz’s total of seven at Munich in 1972. 
His gold medal events, including seven world records (WR), were: 400m individual medley (WR), 4x100m freestyle relay (WR), 200m freestyle (WR), 200m butterfly (WR), 4x200m freestyle relay (WR), 200m individual medley (WR), 100m butterfly and 4x100m medley relay (WR).
He also won six gold and two bronze medals at the Athens Olympics in 2004.  At the 2007 World Championships in Melbourne, Phelps won seven gold medals and broke five world records.