Billboard has released a list of the greatest pop stars of the 21st century, with Beyoncé reportedly taking the top spot. The list appears to include a range of artists, such as Lady Gaga, Britney Spears, and Justin Bieber, although their exact rankings vary. It is unclear how the list relates to a separate recognition of top female songwriters, which is said to include Taylor Swift, Beyoncé, and Ariana Grande.