Biggest Breakout Stars of 2009

In an era in which American Idol and YouTube are the new ways to the top, Lady Gaga blazed her own trail. She's the first artist in history to chart four No. 1 hits off of a debut album, thanks largely to a huge fan-base loyal to the synth-pop tracks she crafts for urban radio and dance clubs. Let's take a look at the other 'Breakout Stars' of 2009

In the months to come, expect music's renegade - a burlesque dancer turned music superstar - to score more award show trophies (she's nominated for five Grammys), sell out more concert dates (her 41-city "Monster Ball" tour kicked off in November) and release another chart-topping album (anticipated in late 2010). She may also do a rock opera produced as a feature-length movie.And lest it stop there, she's collaborating with branding guru Steve Stoute for a line of Gaga-branded electronic sunglasses, much like she dons in concert. It's enough to keep her fans salivating and secure Gaga a spot on our list of music's rising stars, a grouping of artists worth keeping an eye on in the year ahead.

Music's Rising Stars Like Gaga, country music darling Taylor Swift has had a year for the record books as well, selling more albums than anyone not named Michael Jackson. Add to that chart-topping songs, sold-out tour dates and a top-rated Saturday Night Live gig. Come 2010, Swift will spend much of the year on the road, where she'll continue her largely sold-out Fearless tour with performances around the world.The singer-songwriter turned teen sensation made history in November when she became the youngest artist ever to win the coveted entertainer of the year award at the Country Music Awards. She was showered with similar acclaim at the MTV Video Music Awards and American Music Awards, and recently snagged another eight Grammy nominations. She'll have another opportunity to clean up at 2010's Grammy Awards, where she has been nominated in eight categories.

Consider Susan Boyle of Britain's Got Talent. The dowdy Scot was unknown before appearing as a contestant in April, stunning viewers and judges alike with her rendition of the song "I Dreamed a Dream" from the musical Les Miserables. A clip of her performance ricocheted around the Web, where it was viewed more than 300 million times. Her hotly anticipated debut album, I Dreamed a Dream, rolled out in November, and shot to the top of charts around the globe. Up next, Talent judge Simon Cowell has expressed interest in making a documentary film out of Boyle's meteoric rise.

And then there's Adam Lambert, the openly gay runner-up of American Idol's eighth season who continues to court fans and controversy.After an onslaught of cover stories and other headlines, the man dubbed "the wild idol" struck big with For Your Entertainment. Released in November, Lambert's debut album opened at No. 3 on the Billboard 200 with nearly 200,000 copies sold stateside. (It plummeted the following week.)More recently, Lambert put himself in the eye of a media storm when he thrust his crotch at and kissed fellow men onstage at the American Music Awards. But even after Good Morning America canceled a follow-up performance, he told Barbara Walters he had no regrets on her most fascinating people special (he was joined by Michelle Obama, Tyler Perry and Gaga, among others).