World and Olympic records set at the 2008 Summer Olympics metres butterfly, both set in Sydney, remained Olympic records. Michael Phelps of the United States also broke the record for the most gold medals ever won by an Olympian with a total of 14; 8 of which were won during the 2008 Summer Olympics - this was also a world record. <nowiki>*</nowiki> World record split from the 4 × 100 m freestyle relay Note: At the 4 × 100 m freestyle relay final, anchor Jason Lezak swam the fastest 100 m split (46.06); however, this is not considered an official FINA record, as he did not swim the first leg.
Great Britain at the 2008 Summer Olympics may elect to hold Irish citizenship and are able to be selected to represent either Great Britain or Ireland at the Olympics). Additionally some British overseas territories compete separately from Britain in Olympic competition. Great Britain's medal performance at the 2008 Summer Olympics was its best in a century; only its performance at the 1908 Summer Olympics, which Britain hosted in London, resulted in more gold medals being awarded. The total medal count, 47, is also the fourth highest Great Britain has ever achieved, with only the 1908, 2012 and 2016 Games resulting in more medals. Following retests of doping