This chapter critically examines the concept of dark leadership and its implications. It explores a range of dark leadership styles—including toxic, narcissistic, psychopathic, exploitative, and abusive supervision—and highlights how these behaviours manifest within professional contexts and differentiate from positive leadership practices. Drawing on theoretical and practical perspectives, the chapter outlines the characteristics, causes, and consequences of each dark leadership type, underscoring their capacity to undermine trust, collaboration, and long-term performance. It further examines how dark leadership is often composed of overlapping traits that blur the boundaries between distinct styles, making it difficult to categorise and address. Despite these complexities, common outcomes such as reduced employee engagement, organisational dysfunction, and reputational harm are identified as recurring consequences. Through real-world examples and reflection prompts, readers are encouraged to develop awareness and strategies for identifying, managing, and mitigating dark leadership in order to protect and promote sustainable transformation efforts and prevent the urge of toxic organisations.