What is the difference between a pathological liar and a narcissistic person?

Since narcissists are typically very dishonest, there may be little difference observed between pathological liars and narcissists, but there is a difference in the way they think. A pathological liar has a compulsion to lie, and will often lie even when there is no personal gain that can be obtained from that particular lie, although such a person will most definitely also lie for reasons of gaining personal advantage. A narcissist is a person who loves himself or herself to the exclusion of all others, and believes that only he or she has any importance. Other people have meaning only to the extent that they can be used to serve the needs of the narcissist. It is a very nasty kind of personality disorder, which we might succinctly describe as absolute selfishness.