Credit: Todd Williamson/WireImage; Michael Tran/FilmMagic

Britney Spears, the reigning Queen of Twitter, has been surpassed by Lady Gaga—who topped the pop star by about 6,000 followers over the weekend. Gaga is also the leading lady on Facebook with more fans, over 16 million, than Spears and President Obama. But she shouldn't rest easy: Justin Bieber is gaining 800,000 followers a month, making the teen sensation a possible competitor for the throne.