celeboddity
An unpredictable celebrity. An odd-ball celeb that sticks out from other celebrities. They may be crazy, ill, abnormally eccentric, unreliable, have drastically been effected due to drug use, or just acting as if they were one of these things in a publicity stunt or hoax in an attempt to boost their career. When a normally apparently content adult celebrity suddenly radically changes their personality.
example: Joaquin Phoenix is a celeboddity because no one knows for sure what he will do next, he's either hoaxing or ill. Andy Kaufman could be considered a celeboddity as well as David Bowie.