What is the myth origin of the word narcissistic?

Well Greek myth has the man named, Narcissus. The myth goes that this man was very beautiful, but he was also very vain and proud. Eventually the gods grew angry at him for his arrogance and punished him. They did this by making him fall in love with his face that reflected by a pond. He couldn't turn away and eventually wasted away and died. A more contemporary reference would be in Harry Potter with Narcissa Malfoy who was very proud and had believed greatly that her beauty surpassed everyone else's beauty.