Teen Takeover! The Year's Hottest (and Youngest) Stars

Age: 16
The undisputed teen queen – estimated to be worth $1 billion by the time she turns 20 – has another season of her star-making Disney hit Hannah Montana on the way and is branching out with a new non-Hannah movie deal. "Madonna always reinvents herself, and that's what I want to do," says Cyrus, who broke records with this summer's Hannah Montana amp Miley Cyrus: Best of Both Worlds concert movie.

Age: 18
Turning 18 last December was good to the country star, who became the youngest person ever to write and record a chart-topping country song. "I wanted a No. 1 record, and I got that," says the double-platinum "Our Song" singer. Swift, who's been linked to Joe Jonas of the Jonas Brothers, has a simple plan for her career: "I just want to be honest and tell my stories," she told "Redbook.

Age: 16
The Wizards of Waverly Place star has been called the " And the Disney Channel actress – who's rumored to be dating Cyrus's ex, Nick Jonas – is adding recording artist to her resume with her in-the-works debut album. "It's something that I've been wanting to do for a long, long time," she says.

Age: 18
The youngest-ever winner of American Idol, Sparks scored a Top 10 hit this year (for her duet with Chris Brown, "No Air") and performed for millions when she sang "The Star-Spangled Banner" at the Super Bowl. And she's not afraid to take a stand: At the MTV Video Music Awards in September, the former plus-size model spoke out against British comedian Russell Brand's jokes about purity rings.

Age: 16
After starring with her pals the Jonas Brothers in Camp Rock and opening for them on their Burning Up tour, Lovato – whose profile was raised even higher when Miley Cyrus and friend Mandy Jiroux mocked her and BFF Selena Gomez on YouTube – has stepped out on her own. She released a debut pop-rock album, Don't Forget, and has her own Disney show, Sonny with a Chance, debuting next year.

Age: 17
Though he was the runner-up to American Idol season 7 winner David Cook, the quiet teen with the big voice has a rabid fan base – dubbing themselves "Archies." "It's pretty cool," says the singer, who recently released his self-titled debut album and first single, . "People put the time and effort into making signs for you with your name and pictures on it! I do appreciate it."

Age: 19
The flame-haired, pint-sized teen kicked off her year at the Grammy Awards, where her band Paramore was nominated for best new artist. While their album, Riot! was certified platinum, the group set gossip blogs in motion after they canceled a tour due to "personal issues" – rumored to be frustration on the increased focus on Williams. But like No Doubt, who famously dealt with a beloved, iconic frontwoman before them, Paramore rebounded and began work on a new album, due next year.

Age: 19
Grimes went from cult hero on Degrassi: The Next Generation to the halls of West Bev High as good girl Annie Wilson on the new 90210. "It's not as amazingly cheesy as the old one," the Canadian actress says of the remake, which has given her her first high-profile role. "It's so real. The issues are going to hit harder and closer to home."

Age: 15
She successfully followed up her role in the Drake amp Josh movies with iCarly, the breakout Nickelodeon show where she plays accidental Web star Carly Shay. Now the actress is ready to show off her musical chops: After singing on the successful iCarly soundtrack album, which debuted at No. 28 on Billboard's 200 Albums chart, Cosgrove began work on her solo disc, due next year.

Ages: Nick, 16, and Joe, 19 (with Kevin, 21)
The threesome sure packed a lot into 365 days: They won six Teen Choice Awards, starred in the wildly successful Disney Channel movie Camp Rock, had a No. 1 album (A Little Bit Longer) and broke iTunes records as the first band to sell more than 100,000 downloads of three consecutive singles – and that's just the start of Jonas Mania. The platinum-selling band has a new TV series, J.O.N.A.S., a Disney Channel reality show and a 3-D concert movie (following this year's sold-out Burnin' Up tour) hitting in 2009.