The Most Depraved Killers in History. Often, the term 'psychopath' tends to be equated with violent and deranged criminality, but true psychopaths are very different from the way they are portrayed in film or on television. They are aware of the difference between right and wrong: they simply choose to ignore anything that prevents them getting what they want. This book looks at history's most motorious and infamous psychopaths, and seeks to show how their life stories illustrate the classic psychopathic personality traits.