Despite a tight link has been hypothesized between sadistic and grandiose narcissism, to date, little is known about the variables accounting for such relationship. The aim of this contribution is to bridge such gap by investigating the topic among a very large sample of Italian adults. In addition, we aimed to contribute to advancing the field through the validation of the Italian version of the benign and malignant envy scale (I-BeMaS). We administrated self-report questionnaires evaluating sadistic personality (Assessment of Sadistic Personality; ASP), pathological narcissism (Pathological Narcissism Inventory), envy (I-BeMaS), as well as admiration and rivalry (Narcissistic Admiration and Rivalry Questionnaire). Structural equation models were used to test the hypotheses. The I-BeMas showed the expected factorial structure, configural invariance across sex as well as scalar- and metric but not strict invariance. In addition, grandiose narcissism, narcissistic rivalry, and malicious envy positively and significantly predicted the ASP scores. Furthermore, rivalry and malicious envy both mediated the relationship between grandiose narcissism and sadism. Results are discussed in light of theoretical, empirical and clinical implications. The role of envy is stressed, underlying the need for further investigation of this variables, too overlooked in previous contributions.