Straddling the most experimental and mainstream sides of pop with ease, Charli XCX -- aka singer/songwriter Charlotte Aitchison -- is just as comfortable working with cutting-edge producers like SOPHIE as she is touring with Taylor Swift. As a songwriter and collaborator, she helped create some of the biggest pop singles of the 2010s, including Icona Pop's 2012 smash "I Love It" and Iggy Azalea's 2014 chart-topping hit "Fancy." As an artist in her own right, her work spanned the edgy sounds of her 2013 debut album, True Romance, to the more straightforward territory of 2014's follow-up Sucker, which featured the U.S. Top Ten single "Boom Clap."