Generally speaking, a celebrity is someone who seeks media attention and most frequently have extroverted personalities. The desire to be notable is implied by some to be a part of western culture and more specifically the American Dream as a measure of success. Celebrities that shy away from the public eye or keep a very separate private life are called a reluctant celebrity.
A notable example is Kurt Cobain. On the oher end of the spectrum, those that seek out publicity for themselves are often called a media tart whereas those that use their private life as a vehicle for enhanced celebrity status, sometimes desperately, are referred to as a media whore. Examples of this are fake or planned relationships, reality television appearances, celebrity nudity and in extreme cases, scandal or celebrity sex tape.