Taylor Swift named No. 2 greatest pop star of the 21st century by Billboard. Who will be No. 1?
The magazine ranked Swift ahead of Rihanna, Drake, Lady Gaga and Britney Spears, but behind one mystery singer.
Billboard's Greatest Pop Stars: The 10 Greatest Pop Stars Never to Be Greatest for a Full Year
In this sidebar to our Greatest Pop Stars by Year article series, we look at the greatest pop stars to never be officially ...