A rising star

China2012 Summer OlympicsMichael Phelps
Katie Ledecky, the youngest U.S. Olympian in 2012, took home a gold medal in the women's 800m Freestyle in a huge upset over Great Britain's Becky Adlington -- and came within half a second of breaking Adlington's current World Record. Ledcky is just 15 years old and the 2012 Olympics is her... Getty Images