If Duncan had known that his own faithful host was not only going to put his life in danger but also kill him, Duncan would not given Macbeth any honors at all. In Macbeth, a play written by William Shakespeare, Macbeth, the tragic hero in the play, kills Duncan in order to make the witches’ prophesy to him come true. Duncan, King of Scotland, is one of the lesser major characters in this play but plays an important role in emphasizing and clarifying Macbeth’s character.