Impostorism, a phenomenon whereby a person perceives that the role they occupy is beyond their capabilities and puts them at risk of exposure as a “fake,” has attracted plentiful attention in the empirical literature and popular media. However, despite evidence that impostorism is frequently experienced by people in leadership positions, there has been little consideration of why this happens. In this theoretical article, we explain why formal leadership roles—roles that are characterized by elevated expectations, high visibility, and high levels of responsibility—are fertile ground for impostorism experiences. We also discuss how the associated self-conscious emotions of shame and fear, can increase leaders’ risk-aversion and enhance leader role performance, yet at the same time drive emotional exhaustion, and reduce their motivation to lead. This can ultimately inhibit leaders from seeking, claiming, and thriving in leadership roles. We offer individual-, dyadic-, and organization-level contextual characteristics that can either enhance or reduce this phenomenon. We also discuss how supportive organizations can mitigate leadership impostorism. Furthermore, we highlight how women and minority-status leaders may be more vulnerable to this experience and conclude by suggesting the practical implications of the leader impostorism phenomenon for individuals and organizations.