Leaders are prominent figures who stand in the glow of the spotlight. They are subject to, and influence the gaze of a wide range of observers, both inside and outside the organisation. But the shadow a leader casts over the workplace is less visible, even though it can darken the lives of many. The theme of this lecture is to provide insights into the darker side of leadership and to address different aspects of leadership dysfunction. What makes leaders derail? What factors trigger leadership failure? Are there warning signs? What effect does failed leadership have on corporate culture, organisational structure and patterns of decision-making? What can be done to change dysfunctional leadership to an effective one?