Mokgadi Caster Semenya (born January 7, 1991) is a South African middle-distance runner and world champion.
Semenya won gold in the women’s 800 metres at the 2009 World Championships with a time of 1:55.45 in the final. Semenya also won silver medals at the 2011 World Championships and the 2012 Summer Olympics, both in the 800 metres.
Following her victory at the 2009 World Championships, it was announced that she had been subjected to gender testing. She was withdrawn from international competition until 6 July 2010 when the IAAF cleared her to return to competition. In 2010, the British magazine New Statesman included Semenya in a list of “50 People That Matter 2010”.