4. Justin Bieber
2015 will go down in history as the year that The Biebs truly turned it around and became the world's biggest popstar. Yes it seemed that he liked to ask loads of questions (What do you mean? Where are you now? WHAT THE F**K IS GOING ON?). Still, his latest album "Purpose" topped the charts all over the world and we're sure 2016 will still see Bieber reigning supreme.