Quote from : DSM-5 Guidebook: The Essential Companion to the Diagnostic and Statistical Manual of Mental Disorders Book

Narcissistic personality disorder is named for Narcissus, from Greek mythology, who fell in love with his own reflection. Freud used the term to describe persons who were self-absorbed, and psychoanalysts have focused on the narcissist's need to bolster his or her self-esteem through grandiose fantasy, exaggerated ambition, exhibitionism, and feelings of entitlement.