Psychopathy originally emerged as a clinical personality disorder (PD) but has since migrated into mainstream personality research. While some traits like risk-taking and charm might be beneficial in business settings, psychopathy, even at non-clinical levels, is considered the most malevolent aspect of the Dark Triad. Characterised by manipulativeness, lack of empathy, impulsivity and antisocial behaviour, these traits often lead to unethical actions in organisational settings, such as deceit, bullying and abuse of power, significantly harming workplace morale and effectiveness. This chapter starts by providing some background into psychopathy and then describes the main scales designed to measure this DT personality. It then covers the implications of having psychopaths in the workplace, including a real case study. Finally, it provides some more case studies, examples of psychopathic individuals who appear in literature and on the global stage.