Justin Bieber is the first teen idol to break through because of YouTube. He was discovered singing on the site by Scooter Braun when he was just 13. After teaming up with Usher (who saw huge potential in the kid), Bieber was recording his debut album and gearing up for world domination. In late 2009 he released My World, and landed a hit with "One Less Lonely World." Girls across America took their Jonas Brothers posters off the wall and put up Justin photos. It's nearly three years later and Bieber is still king. His new single "Boyfriend" crossed over to the adult market, and his relationship with Selena Gomez has turned both of them into bigger stars than they'd be on their own. It's unclear where things go from here, especially since a new five-piece act from England is threatening to steal his thunder.