Who is the most vicious human being that literature has ever produced?

Who is the most vicious human being that literature has ever produced? Perhaps Nikolai Stavrogin in Dostoyevsky’s ‘The Devils’, or Iago in Shakespeare’s ‘Othello’, or Thomas Sutpen in William Faulkner’s ‘Absalom, Absalom!’, or James Durie in R. L. Stevenson’s ‘The Master of Ballantrae’. James Durie carries on the most savage and intolerant ill-treatment against his good-natured younger brother Henry.
You know, there are many people who ill-treat others, but they have their practical reasons to do so. James Durie is very unusual in that, and he ill-treats Henry, presumably because he is good-natured unlike him. So his ill-treatment continues as long as Henry is good-natured. Considering that the moment James dies, Henry suddenly dies with no convincing reason, one may well be pretty sure that Stevenson thought that James’ character and Henry’s character coexist in one and the same person. In that sense, this is a book parallel to his much more famous book ‘Dr. Jekyll and Mr