Most past research has focused mainly on the personality of the victims of bullying and not on the personality of workplace bullies. Some researchers have suggested that bullies and their victims may share bully-typifying personality traits. The aims of this study were to find out what characterizes the personalities of workplace bullies and their victims, and to investigate the relationship between the Dark Triad, HEXACO and workplace bullying. We tested three hypotheses. H1: Machiavellianism and Psychopathy, but not Narcissism, predict the use of bullying tactics (i.e., bullying perpetration). H2: (Low) Honesty-Humility, (low) Agreeableness and (high) Extraversion predict the use of bullying tactics. H3: Honesty-Humility moderates the association between Machiavellianism and the use of bullying tactics. Employees in southwestern Sweden (N = 172; 99 women) across various occupations and organizations were surveyed. Negative Acts Questionnaire-Perpetrators (NAQ-P) and Negative Acts Questionnaire-Revised (NAQ-R) were used to assess the use of bullying tactics and victimization. NAQ-P was correlated with NAQ-R (r = .27), indicating some overlap between the use of bullying tactics and victimization. NAQ-P was correlated with Machiavellianism (.60), Psychopathy (.58), Narcissism (.54), Agreeableness (-.34), Honesty-Humility (-.29) and Extraversion (.28). The results of linear regressions confirmed H1, but only partially confirmed H2: Machiavellianism, Psychopathy, (low) Agreeableness and (high) Extraversion explained 32%, 25%, 27% and 19%, respectively, of the variation in the NAQ-P. Replicating past research, NAQ-R was correlated with Neuroticism (.27), Extraversion (-.22), Openness (-.19) and Conscientiousness (-.16). Neuroticism explained 25% and (low) Extraversion 17% of the variation in the NAQ-R. Confirming H3, Honesty-Humility moderated the relationship between the NAQ-P and Machiavellianism. We conclude that bullies, but not their victims, are callous, manipulative, extravert and disagreeable, and that dishonest Machiavellians are the biggest bullies of all. In practice, the victims of workplace bullying need strong and supportive leadership to protect them from bullies with exploitative and manipulative personality profiles.