Psychopaths are associated with psychopathic personality disorder or psychopathy; sufferers show traits and symptoms of antisocial personality disorder or narcissistic personality disorder. Therefore they lack and have an absence of empathy, guilt and/or emotional connections; as a result they tend to be violent, twisted and also cannot be remorseful, exceptions aside.

As stated by Lecter's quote above, Psychopaths are NOT crazy or psychotic, and are often mistaken for being so. Psychopaths are completely aware of reality while psychotic people are polar opposites; they hear voices, hallucinate, and often do not fully understand what they are doing.

Sociopathy is a version of psychopathy. Psychopaths however are often more intelligent, while sociopaths are good liars who don't have many feelings, but understand others' feelings way too much. A lot of sociopaths have a facade they use in order to blend into society. However, this does not mean that every sociopath is villainous; in fact, most sociopaths in real-life are people living a completely normal life, and in fiction, some may even be heroic (though as anti-heroes).

Psychopathy and sociopathy are usually persistent conditions from birth, but it can be induced by a succession of horrific events that twisted the sanity of said characters.

Also, just because a villain is Vengeful or Wrathful and therefore adapts violent tendencies doesn’t necessarily make them Psychopaths unless they are that particularly antisocial in nature.

It is also the opposite of sympathetic heroes.