Introduction to 21st Century & Our 25 Honorable Mentions

Welcome to the 25 Greatest Pop Stars of the 21st Century! Before we start counting down our top 25 over the next four months, Billboard's deputy editor Andrew Unterberger, executive director of music Jason Lipshutz and staff writer Kyle Denis quickly run through the best of the rest -- the pop stars from Nelly to Billie Eilish who were the absolute toughest cuts from our list.

Learn more about your ad choices. Visit megaphone.fm/adchoices