Through the 2008 Games, that would be swimmer Penelope Heyns with 2 gold medals. She won gold in the 100 meter breaststroke and 200 meter breaststroke at the 1996 Games in Atlanta.
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Michael Phelps 8 gold medals
Steve Redgrave (5).
18
Through the 2008 Games in Beijing, that is Eduardo Mangiarotti who won 6 gold medals in fencing between 1936-1960.
10 gold medals
Through the 2008 Games in Beijing, that is Halil Mutlu who won 3 gold medals in weightlifting between 1996-2004 and Naim Süleymanoğlu who won 3 gold medals in weightlifting between 1988-1996.
The most successful and decorated Olympic athlete as of 2014 is Michael Phelps. He has 22 Olympic medals with 18 being gold medals.
The Water Cube
Mark Spitz is famous for winning seven gold medals at the 1972 Summer Olympics.
150 medals or about 100
Michael Phelps' first Olympics was the 2004 Games in Athens where he won 6 gold medals and 2 bronze medals.