Narcissism is a term first used in relation to human psychology by Sigmund Freud. It was derived from the figure of Narcissus in Greek mythology (right) who was doomed to fall in love with his own reflection in a pool of water. It is a character trait concerned with self regard. Everyone has some degree of narcissism. However, narcissism can also manifest, in an extreme form, as a severe personality disorder such as NPD.

http://en.wikipedia.org/wiki/Narcissism_(psychology)