The youngest ever competitor on "Dancing with the Stars," 17 year-old Olympian and high school junior 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. She teams up with former "Dancing with the Stars," champ Mark Ballas, who returns for his fourth season.

The youngest ever competitor on "Dancing with the Stars," 17 year-old Olympian and high school junior 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. She teams up with former "Dancing with the Stars," champ Mark Ballas, who returns for his fourth season.