What's in a name? Well, a lot actually. For one thing there would be a lot of confusion if singer Katy Perry went by her birth name: Kathryn Hudson. And, face it, Demetria Gene Guynes doesn't have nearly the ring to it as Demi Moore.
Whether it's a nickname, easier to pronounce, something to prevent confusion from being mistaken for someone else, or a complete moniker fabrication, many a celebrity goes by a name other than the one they were given at birth.