Narcissism, a trait reflecting egocentric exceptionalism and social selfishness, has captured scholarly interest due to its intricate composition and social implications. The construct is polyhedric, comprising several key forms: grandiose versus vulnerable, agentic versus communal, admirative versus rivalrous, collective versus individual. These forms can be integrated into structural models that add predictive power or process models that add explanatory power. The narcissistic nucleus is argued, and partly shown, to be brittle in the face of self-threat. The nucleus may derive from being overvalued, or inconsistently socialised, by parents. Narcissism entails intrapersonal benefits, as it can confer psychological health, buffer against adversity, and facilitate performance. But it can also be an interpersonal and societal liability, partly remediable with narcissism-reduction interventions. Narcissism is a polyhedric construct. It assumes different forms: grandiose versus vulnerable, agentic versus communal, admirative versus rivalrous, collective versus individual. These predict unique outcomes, but can be integrated under structural models that contribute predictive power or process models that contribute explanatory power.The narcissistic nucleus may be unstable, especially for some forms (vulnerable, collective).Parental overvaluation may predict grandiose narcissism, although the role of parental inconsistency in predicting other forms of narcissism (e.g., vulnerable) is worth investigating.Narcissism may entail some intrapersonal benefits for narcissists (especially grandiose ones), such as psychological health, serving as a buffer against adversity, and motivating better performance.Given that narcissism entails interpersonal and social costs, laboratory techniques have addressed ways to curtail it, although long-term and behaviour-oriented interventions are needed.