Niall Horan, 'Flicker'
The blond heartthrob was the folkie of One Direction, with a subtle delivery and a penchant for playing acoustic guitar live. His solo debut will build on that identity, inspired by Seventies California rock (he's called mentor Don Henley "Dad"). So far it's working: The guitar-heavy single "Slow Hands" is a pop hit. Horan spent six months writing with a crew that had previously crafted 1D hits. "I wanted this album to be completely personal," Horan says, "therefore, the best way for me to get what I wanted out of the songs was to write them with friends."