21 Under 21: Demi Lovato
21 Under 21: Demi Lovato

No. 8: Demi Lovato

Birthdate: August 20, 1992 (age 18)

Why She's Hot: Demi Lovato, who got her start on TV as one of Barney's little friends, has used her roles in Disney Channel ventures like "Sonny with a Chance" and the "Camp Rock" franchise to forge a successful singing career. The 18-year-old Dallas native went all the way to no. 1 with her sophomore disc "Here We Go Again" in 2009. Lovato is currently working on her follow-up disc, touring with her "Camp Rock 2" co-stars the Jonas Brothers, and lighting up red carpets around the globe.

Video Below: Demi chats with Billboard backstage on tour with the Jonas Brothers

Next: Willow Smith