Sure, puberty is the bane of the boy band's existence. But, hey, the New Kids On the Block are still hangin' tough -- that's a song pun, kids -- in their 40s. Signed by Simon Cowell's record label, One Direction has put up big boy numbers since its 2011 debut.
In their favor: According to critic Neil McCormick of the London Telegraph: "It took the meteoric rise of Justin Bieber . . . to demonstrate that there was still a huge appetite for clean cut, wholesome, whiter-than-white, middle class parent friendly pop: cute boys advocating puppy love."
Biggest threat: Facial hair.