Psychopath: A person with an antisocial personality disorder, manifested in aggressive, perverted, criminal, or amoral behavior without empathy or remorse. (The Free Dictionary)
Psychologist Kevin Dutton:
Source: Big Think
Kevin Dutton is the author of The Wisdom of Psychopaths: What Saints, Spies, and Serial Killers Can Teach Us About Success.
Kevin Dutton's website: Prof. Kevin Dutton
The difference between a psychopath and a sociopath: Psychopath vs Sociopath.
If somebody asked you to do a random word association on the word "psychopath", the grim words "serial killer" would probably appear somewhere on your list. But many of the characteristics of psychopaths are shared by politicians — and heroes. Yes, the psychopath who would burn down your house is in many ways similar to the hero who would rescue your loved ones from the same burning house. (Source: ABC Science: Spot the psychopath near you. )
When most people think of psychopaths, they think—with a shudder—of serial killers like Ted Bundy, who seem to show no remorse or even understanding that what they do is morally wrong.
Psychopathy —also called sociopathy—is indeed defined by lack of empathy, callousness and complete disregard for anything or anyone else other than one's selfish needs. But although all psychopaths meet the criteria for what the diagnostic manual calls "antisocial personality disorder"—of which psychopathy is the most extreme case—not all of them are ruthless murderers. (Source: Why Do Some People Become Psychopaths? )