There is a growing literature that links the naracissistic personality style with aggressive behaviour, but apart from ego-threat sensitivity, there are a few factors that have been examined as potential mediators of this effect. In addition, most of the research to date has examined the more overt/grandiose aspects of narcissism, with almost no research investigating the relationship between aggression and the more covert/vulnerable aspects of narcissism. In a questionnaire study of 309 participants it was found that both overt and covert narcissism were significantly positively correlated with trait aggression, as well as with self-reports of actual aggressive behaviour. Of the two narcissism types, covert narcissism had the strongest relationship with aggression. The covert narcissism-trait aggression link was significantly mediated by a hostile mindset, shame-proneness and trait anger, and the covert narcissism-actual aggression link followed the same pattern. Whereas the overt narcissism-trait aggression link was robustly mediated by trait anger, with a hostile mindset being a marginally significant mediator, the overt narcissism-actual aggression link was most strongly mediated by hostile mindset, with trait aggression also partially mediating the effect. Ego threat sensitivity, rejection sensitivy, and generalised threat responsiveness did not mediate narcissism and aggression in any analysis, and there was no evidence that any effect was due to increased guilt-proneness. The implications of these findings for the ego-threat hypothesis, as well as for more general theories of narcissism and aggression, are discussed.