13. Cody Simpson: 21 Under 21 (2014)
Birthdate: Jan. 11, 1997 (Age: 17)
Last Year's Rank: 9
Why He's Hot: This is Simpson's fourth consecutive year on Billboard's 21 Under 21 list, and it doesn't seem like he's disappearing anytime soon. The Scooter Braun client followed up 2013's top 10 album Surfers Paradise with November's acoustic album The Acoustic Sessions. After a brief stint on Dancing with the Stars in early 2014, Simpson departed his record label and currently remains unsigned -- although likely not for long. In the meantime, there are buzzing rumors that Simpson is teaming up with pal Justin Bieber for some kind of acoustic collaborative album in the near future. We're keeping our fingers crossed!
Billboard's 2014 21 Under 21 List