Macbeth: King of the Greater Evil
In most bad situations, there are several contributing factors. The story of how Macbeth became king only to end up dead is no different. Almost every character in Macbeth influenced exactly how things happened (or why they happened). Macbeth, Duncan, Lady Macbeth, Banquo, and the witches seem to be the guiltiest in this story though. However above all else, Macbeth is the most culpable. Macbeth is involved in every single situation in this play (after all the play is named after him), from the witches' predictions, to his own death.
Macbeth could have heard the witches' predictions and thought nothing of it. He did not really believe them at first, but he ended up believing them enough to think about what was in his way. He also believed in the predictions enough, to share them with Lady Macbeth. Of course, Lady Macbeth does not help the situation, by persuading Macbeth to kill Duncan simply because she is avaricious and wants to be Queen and her husband to be King.
Macbeth had a mind of his own and he could make his own decision. The other murders that Macbeth was involved in were not committed by him, but were ordered by him. The people who did the killing had no choice, they had to do it, because they worked for Macbeth. Macbeth knew this and was a bit guiltier in these murders then Lady Macbeth was when she urged him.
A turning point is when Lady Macbeth is talking to Macbeth in Act 1.7, and Macbeth responds "Prithee, peace. I dare do all that may become a man; Who dares do more is none." Lady Macbeth then continues persuading her husband about how much more of a man he would be to complete...