If you follow my writing, you know that I don't think much of the generalization we call 'personality.' I'm far more interested in behavior. So whenever I see 'Narcissistic Personality Disorder,' I think of it more as a narcissistic behavioral disorder. That said, the National Institutes of Health defines Narcissism as a personality disorder, so there's no point in arguing the point. They say the disorder is characterized by a pervasive need for attention and admiration combined with a lack of concern or empathy regarding other people. The American Psychiatric Association publishes the Diagnostic and Statistical Manual of Mental Disorders, (DSM-IV-TR) where it provides the diagnostic criteria for the Narcissistic Personality Disorder (301.81, p. 717). Click the link to read these criteria. Five or more of these criteria must be met in order to make the diagnosis of NPD. Here's another link to the diagnostic criteria, which are explained and embellished a bit for clarity.
I've read the claim that pathological narcissism is a condition that afflicts mostly men, with some estimates that 75% of the recognized and diagnosed cases are male. My experience as a coach and counselor tells me otherwise. Just as intelligence and stupidity are equally divided across gender lines, so is narcissism. Male and female narcissism may express themselves differently, along stereotypical gender roles. For example, the male narcissist may be consumed with power, status and achievement, whereas the female narcissist may be obsessive about her body and beauty, sexual characteristics, home and family. But its narcissism all the same.
Some narcissists are cerebral (it's all about their intellect and achievements), and some are somatic (it's all about their physical characteristics and sexual prowess). Some are exhibitionists (energetic and outgoing), some are fragile (feeling inadequate and lonely), and some malignant (exploitive of others...malignant means it gets worse through time, and contains an element of sadism).
Pathological narcissists may project an image of themselves as brilliant, clever, even heroic, but the fact is that the only time a narcissist gives of themselves is when the desired result is self serving, like Lex Luthor in the Superman mythos who always has a hidden agenda. If they admit to some kind of character flaw or weakness, it’s very likely they are revealing it for personal gain.
Perhaps driven to hide any weakness so as never to be exploited or diminished by others, some narcissists erect a facade (a false front) of confidence in their own ‘specialness,’ be it mental, emotional, practical or morally superior. They patrol this facade armed with a sense of entitlement that things should always go their way, and attack or undermine anyone who gets in their way.
Or, they may create a facade of victimhood, regularly making the biggest imaginable deal out of the smallest imaginable grievance. Narcissists often play the victim in order to leverage the emotional state of those on whom they prey.