award competitors points for executing moves such as takedowns, escapes, and reversals. Unless one wrestler pins his opponent's shoulders to the mat, thus earning an immediate victory, the outcome of a match is determined by who has the greater point total.
With this information in mind, one can fully appreciate the magnitude of American lightweight-division freestyle wrestler Dan Gable “winning gold at the 1972 Olympic Games in Munich, Germany while not giving up a single point” in six matches. I have not been able to find records on the frequency of wrestlers going unscored upon in an entire Olympic competition, but suffice it to say, it's pretty rare!
Aleksandr Karelin, practitioner of Greco-Roman wrestling, which "forbids holds below the waist," won three straight Olympic gold medals spanning 1988-1996. As noted on Karelin's Wikipedia page, the super-heavyweight went "13 years [1987-2000] undefeated in international competition and six years without giving up a point." Karelin's name presumably was well known to American viewers of the 2000 Olympics, as it was Rulon Gardner of the U.S. who prevented the Russian from taking a fourth consecutive gold. This TIME Magazine article recounts the 2000 final between Gardner and Karelin.
Women's wrestling has been part of the Olympics since 2004. Japan's Saori Yoshida (freestyle) won gold medals in 2004 and 2008, while holding winning streaks as long as 119 matches during her international career. Yoshida will be trying for a third straight gold in London.
Bleacher Report has compiled a slideshow of great Olympic wrestling moments, which can be accessed here.