Justin Bieber, One Direction Top Billboard 21 Under 21 List

Demi Lovato, Selena Gomez and Nick Jonas also make list of Music's Hottest Minors.

It doesn't take a formal list to know that Justin Bieber and the guys of One Direction are biggest stars under 21 right now. So, it's not really surprising they top Billboard 's 21 Under 21: Music's Hottest Minors 2012.

Justin Bieber is the hottest youngster on the scene. He's currently prepping a world tour and just wrapped up a music video for his latest single, the Nicki Minaj-assisted "Beauty and a Beat," off his #1 Believe album.

"I was very involved in the process [of making this album] — I played instruments, produced, wrote — so I want people to know it's not all hype," he told MTV News about prepping his highly anticipated album. "I want people to know I've been working hard on my music. Focus on the music. Don't think I'm just this product pushed out there. I work hard, and music is really important to me."

Runners up One Direction took their fandom international when they dropped their debut album, and they haven't looked back. The British boy band is prepping the release of their sophomore album release, Take Me Home, and have fans buzzing with excitement for the release of its lead single, "Live While We're Young."

Demi Lovato is the only lady in the top three. Sitting at #3, the "X Factor" judge has reinvented her career and launched herself as a pop star (her song "Give Your Heart A Break" recently went to #1 on the charts).

"The reception for my single is so amazing," she told MTV News. "It's been going up the charts for a while now and right now I actually have my first #1 single, so that's really exciting for me. It means so much to me. I never thought I'd be blessed enough to have this opportunity and here I am."

The remainder of the top 10 is incredibly diverse. "American Idol" singer Scotty McCreery narrowly missed the top spots at #4, with rap sensation Mac Miller right behind at #5. Bieber's best girl, Selena Gomez, fell to #6 this year after a top-three appearance on the 2011 list. EDM star Porter Robinson leaped to #7 after appearing on the list last year at #18.

One-time "X Factor" contestant Cher Lloyd is #8, followed by Odd Future's Earl Sweatshirt, who beat out Nick Jonas. Nick made the top 10 thanks to the recent reunion of the Jonas Brothers and his presence on Broadway.

The rest of the list is filled out with a mixed bag of viral sensations, international stars and small-screen talent including, diva-in-training Jackie Evancho (#11), Cody Simpson (#12), boy banders Mindless Behavior (#13), YouTube sensations Megan and Liz (#14), Korean pop singer IU (#15), Disney princess Bridgit Mendler (#16), Mexican pop band 3Ball MTY (#17), Miley Cyrus (#18), up-and-coming dance producer Madeon (#19), Disney star Ross Lynch (#20) and Victoria Justice (#21).

Was one of your favorite minors left off the list? Let us know in the comments!