At the age of 16, he auditioned for The X Factor, and the rest is history. One Direction, formed on the show in 2010, went on to become one of the most popular groups of the decade, with sales even surpassing the Beatles. Horan was one of the group's principal songwriters and a fan favorite with his baby-faced good looks and sweet tenor. After five albums in five years and the loss of one of their most popular members (Zayn Malik), One Direction took a well-deserved hiatus beginning in January 2016. Later that year, Horan announced he had signed a solo deal with Capitol. His debut solo single, the romantic acoustic ballad "This Town," was released in September, drawing comparisons with Ed Sheeran and reaching number nine on the U.K. singles chart. Two further singles appeared -- "Slow Hands" and "Too Much to Ask" -- before his debut solo record, Flicker, was released in October 2017. Inspired by the sounds of Fleetwood Mac and the Eagles, the album also featured an appearance by Maren Morris on "Seeing Blind." ~ John D. Buchanan