Most of the members from U.K. boy band One Direction are still teenagers: Liam Payne, 19, Niall Horan, 19, Harry Styles, 18, and Zayn Malik, 19, (Louis Tomlinson is 21). Earlier this year the group became the first British band to debut on top of the Billboard 200 list when "Up All Night" sold over 176, 000 copies during its first week of release in America. These guys are massively popular with teenage girls.