Grandiose narcissism is a multifaceted psychological construct characterized by an inflated sense of self-importance, entitlement, and a pervasive need for admiration. Unlike vulnerable narcissism, which manifests as hypersensitivity and defensiveness, grandiose narcissism is marked by social dominance, assertiveness, and interpersonal charm. This chapter provides a comprehensive examination of grandiose narcissism by integrating theoretical perspectives, empirical research, and clinical insights. It outlines the core features of grandiose narcissism, including fantasies of unlimited success, superficial interpersonal relationships, and low empathy, and situates these within contemporary trait-based and clinical frameworks. The chapter also addresses dimensional models, such as the Agency-Communion Model and the Narcissism Spectrum Model, which conceptualize narcissism as a dynamic interplay of self-enhancement motives and interpersonal strategies. Genetic and environmental influences are discussed, highlighting the moderate heritability of narcissistic traits and the role of non-shared environmental factors. The chapter explores developmental pathways, including parenting styles and attachment patterns, as well as cultural influences on narcissistic expression. Interpersonally, grandiose narcissists often establish instrumental relationships that ultimately lead to conflict and relational dissatisfaction. In occupational contexts, they may demonstrate both charismatic leadership and exploitative behaviors. Finally, the chapter considers the psychological adjustment and social outcomes associated with grandiose narcissism and calls for interdisciplinary research that integrates biological, psychological, and sociocultural dimensions. By advancing the understanding of grandiose narcissism, this chapter aims to inform both research and practice, with implications for future research.