Narcissism and psychopathy are so fascinating because they can simultaneously help individual leaders advance their careers while hurting the people and organizations they lead.

A third defining feature of psychopaths is their lack of empathy. They don’t care about what others are thinking or feeling, despite being able to understand those feelings. As a result, psychopaths are known for their cold dispositions. The absence of empathy is probably a major cause for their lack of moral constraints; it’s obviously much harder to behave in prosocial ways when you don’t care about people.

Interestingly, toxic cultures can be regarded as the product of psychopathic leaders, because leaders tend to create cultures in their own image. In that sense, psychopathy is self-perpetuating.

To be clear, many charismatic people are neither psychopathic nor narcissistic, in the same way that many psychopathic and narcissistic people have absolutely no charisma. But when these darkside traits are lubricated with charisma, they can make leaders pretty lethal. The more we rely on charisma as a marker of leadership potential, the more we risk ending up with toxic leaders who are exploiting their charms and influence to grab power and manipulate their followers.

Dark side traits can be divided into three groups. The first group is the distancing traits—obvious turnoffs that push leaders away from other people. Being highly excitable and moody has this effect, for instance; or having a deeply skeptical, cynical outlook, which makes it hard to build trust. Another example is leisurely passive-aggressiveness—pretending to have a relaxed, polite attitude while actually resisting cooperation or even engaging in backstabbing.

The second group of traits has, in contrast, seductive qualities; they are geared to draw people in. These traits are often found in assertive, charismatic leaders, who gather followers or gain influence with bosses through their ability to manage up. Narcissism and psychopathy are in this group.

The third group contains ingratiating traits, which can have a positive connotation in followers but rarely do in leaders. Someone who is diligent, for instance, may try to impress the boss with meticulous attention to detail, but this attention can also translate into preoccupation with petty matters or micromanagement of the person’s own direct reports. Someone who is dutiful and eager to please those in authority can easily become too submissive.