The youngest ever competitor on “Dancing with the Stars,” 17 year-old Olympian Shawn Johnson was the gold medalist in balance beam at the 2008 Summer Olympics in Beijing, where she also earned three silver medals in the team, floor exercise and individual all-around categories. The current two-time National Champion and high-school junior, Shawn appeared on a limited edition Cheerios box in early 2009, led the pledge of allegiance at last year’s Democratic National Convention in Denver, was a headliner of last fall’s Tour of Gymnastics Superstars, and was named Choice Female Athlete at the 2008 Teen Choice Awards. Her debut biography, “Shawn Johnson -- Olympic Champion: Stories Behind the Smile,” was released in December.