Psychologists Delroy Paulhus and Kevin Williams named the 'Dark Triad' in 2002: narcissism (grandiosity, need for admiration, entitlement), Machiavellianism (strategic manipulation, cynical view of others, willingness to deceive for advantage), and psychopathy (impulsivity, low empathy, thrill-seeking). Crucially, these aren't three separate diagnoses most people either have or don't — they're measured as dimensional traits everyone has some amount of, with only a small tail of the population scoring high enough across all three to be genuinely dangerous. A person can be quite narcissistic without being especially manipulative, or highly strategic without lacking empathy at all.
The traits correlate with each other but aren't identical, and workplaces select for some of this more than people expect: modest Machiavellianism and narcissism show up more often in competitive, high-status roles, partly because unapologetic self-promotion and strategic ruthlessness genuinely help people get promoted in certain environments, at least in the short term. The practical use of the framework isn't diagnosing people you dislike — it's recognizing the specific combination (charm plus a willingness to use people plus no apparent guilt about it) early enough to set boundaries before real damage is done, rather than after.
On his first day as a psychologist at the British Columbia Penitentiary in the early 1960s, fresh out of graduate school with no clinical training and no mentor, Hare met an inmate he calls "Ray." Ray walked in, sat down, and opened with, "Hey, Doc, how's it going? Look, I've got a problem. I need your help." Then, still smiling and holding intense, unbroken eye contact, he pulled out a knife and waved it in front of Hare's face. Hare's hand was near the office panic button; he chose not to press it, sensing Ray was testing him rather than threatening him. Ray then explained, conversationally, that the knife wasn't for Hare — it was for another inmate. Hare later built a career studying exactly this profile: total ease with a situation that would panic almost anyone, paired with no discomfort at all about the ethical weight of what was being described.