psychopath

psykopaatti A person with a personality disorder indicated by a pattern of lying, cunning, manipulation manipulating, glibness, exploiting, heedlessness, arrogance, delusion of grandeur|delusions of grandeur, sexual promiscuity, low self-control, disregard for morality, lack of acceptance of responsibility, callousness, and lack of empathy and remorse. Such an individual may be especially prone to violent and criminal offenses.
A person diagnosed with antisocial or dissocial personality disorder.
A person who has no moral conscience.
A person who perpetrates especially gruesome or bizarre violent acts.