The dark-ego-vehicle principle (DEVP) suggests that individuals with so-called dark personalities (e.g., high narcissistic traits) are attracted to political and social activism that they can repurpose to satisfy their specific ego-focused needs (e.g., signaling moral superiority and manipulating others) instead of achieving prosocial goals. Currently, research on the DEVP is still rare. With two pre-registered studies, we sought further evidence for the DEVP by examining the associations of pathological narcissistic grandiosity with involvement in LGBQ activism (Study 1) and gender identity activism (Study 2). Socioeconomically diverse samples from the USA (Study 1; N = 446) and the UK (Study 2; N = 837) were recruited online via the research-oriented crowdsourcing platform Prolific. Individuals completed the Pathological Narcissism Inventory as well as measures of involvement in activism. Moreover, we assessed different covariates (e.g., altruism), and potential correlates within the narcissism–activism relationship (i.e., virtue signaling, dominance, and aggression). In addition, we examined potential relationships between other dark personality variables (e.g., psychopathy) and activism. In both samples, higher pathological narcissistic grandiosity was related to greater involvement in activism. As expected, virtue signaling was consistently involved in the relationship between pathological narcissistic grandiosity and activism. However, neither dominance nor aggression was related to individuals’ involvement in activism. The results did also not consistently support a relationship between higher psychopathy and greater involvement in activism. Overall, the findings help to further specify the DEVP.