There are stage names, and then there are alter egos. Many musicians adopt a moniker besides the one on their birth certificate to become performing artists and public figures. But a rare few in pop history have decided that even that initial public identity they’ve chosen to put forward doesn’t quite encompass their personality or their musical abilities, and create a new character or persona. Sometimes these musical alter egos have released entire albums of their own, sometimes they just pop up for a song and/or video here and there. Sometimes they sound radically different from the artist’s usual work, sometimes the distinction is subtle (or nonexistent). Here are The 20 Best Alter Egos in Pop Music History.