Jeffrey Dahmer. Richard Kuklinski. Charles Manson. Kenneth Bianchi. Dennis Rader. Bernie Madoff. These are a few of the most infamous psychopaths of the past 50 years.  

While many people who fit the profile of a psychopath aren't serial killers or notorious criminals, they share a number of the same characteristics. And that can make them nightmares in the workplace.

"What's fundamentally different about [psychopaths] is that they do not have a conscience regarding their conduct, no matter how catastrophic the consequences might be," explained Kelly Wilson, president and director of forensic services for Edina, Minn.-based PsyBar LLC, during a presentation at the 2013 National Safety Congress and Expo in Chicago.

"Many of them are literally unable to experience human attachment or genuine human emotion."

Even if their behavior isn't criminal, psychopaths bring a number of toxic traits into the workplace, Wilson explained. Citing the research of the late Hervey Cleckley – a pioneer in the study of psychopathy – Wilson noted that psychopaths tend to be:

  • Superficially charming and gregarious.
  • Inhumanly calm.
  • Unreliable.
  • Dishonest and insincere.
  • Antisocial.
  • Arrogant and egocentric.
  • Unresponsive to interpersonal relations.
  • Outrageous and uninviting in their behavior.

Psychopaths, Wilson noted, also tend to have "an inclination for breaking rules and pushing the limits of acceptable behavior" – which can undermine workplace-safety efforts in a heartbeat.   

In addition to these and other common characteristics, psychopaths often share a chameleon-like ability to blend into normal society without being noticed (a concept introduced in Cleckley's landmark book "The Mask of Sanity").

"Psychopaths just have a stillness about them, where you don't really know what's going on," Wilson said. "It's called the mask of sanity – where they put on their everyday face, but what's behind it is something altogether different."