At their peak, One Direction were considered the biggest boy band in the world. Today, they're still regarded as one of the most successful boy bands in history, with the likes of the Backstreet Boys ...

LONDON, ENGLAND - NOVEMBER 11: (L-R) Harry Styles, Niall Horan, Louis Tomlinson, Zayn Malik and Liam Payne of X-Factor band One Direction attend the Harry Potter And The Deathly Hallows: Part 1 World ...