Justin Bieber & Friends

In the years since Justin Bieber went from online phenomenon to superstardom, his contact list has filled up with major names. He dueted with mentor (and fellow teen sensation) Usher and mile-a-minute MC Ludacris early in his career, and his collaborations with nouveau troubadour Ed Sheeran and EDM alchemist Skrillex pushed him past his R&B roots. Pals like Carly Rae Jepsen fill out his galaxy.