Drake
The rapper used to star on "Degrassi: The Next Generation," where he was credited as Aubrey Drake Graham. In 2006, when his music career started to pick up, he dropped his first name and went by Drake only. Looks like the using one name has been successful for him.
Portia de Rossi
Former model and actress Portia de Rossi was born Amanda Lee Rogers. She credits completely changing her name to the fact that she was uncomfortable with her identity for so long. Portia comes from Shakespeare's "The Merchant of Venice."