From Leader Narcissistic Rivalry to Unethical Pro-Organizational Behavior: The Mediating Role of Workplace Ostracism and the Moderating Role of Underdog Expectations.

Unethical pro-organizational behavior (UPB) is gaining scholarly attention due to its harmful consequences, yet limited research explains how employees' perceptions of leaders' personality traits drive such behavior. Drawing on conservation of resources theory and the Narcissistic Admiration and Rivalry Concept, this study examined whether and how perceived leader narcissistic rivalry predicts employee UPB. We argue that leaders high in narcissistic rivalry devalue and exclude others, increasing workplace ostracism. Ostracism, in turn, depletes employees' psychological resources and motivates UPB as a compensatory strategy. We further propose that underdog expectations amplify this effect by shaping employees' interpretations of exclusion. Using a three-wave, time-lagged survey of 383 full-time employees in South Korea and analyzing data with PROCESS Macro, results show that perceived leader narcissistic rivalry positively predicts workplace ostracism. Workplace ostracism increases UPB and mediates the relationship between leader narcissistic rivalry and UPB. Moreover, underdog expectations strengthen the positive association between ostracism and UPB, with stronger effects among employees high in such expectations. These findings identify workplace ostracism as a key resource-depletion mechanism linking leader narcissistic rivalry to unethical behavior and highlight underdog expectations as an important boundary condition. They highlight the need to manage narcissistic leadership, reduce ostracism, and strengthen ethical norms.