What irony is revealed in the play Macbeth?

There are several instances of irony in the play, some situational and some dramatic.

A good example of situational irony is Macbeth's killing Duncan to gain the throne, thinking only of the power and wealth he will enjoy as the new King of Scotland. However, after murdering Duncan and being crowned, Macbeth cannot enjoy any part of his new position. He continues to kill in order to maintain power until he becomes a despised tyrant who is destroyed by his own people.

Another good example of situational irony concerns Lady Macbeth. She takes part in Duncan's murder with no hesitation or guilt. She berates Macbeth for being weak when his conscience bothers him about Duncan's murder. She is cold and calculating. However, at the end of the play it is Lady Macbeth who is overwhelmed with guilt and eventually kills herself.

Dramatic irony functions a bit differently. It is created in drama when the audience knows and understands more than the characters do. An excellent example of dramatic irony is found when King Duncan comes to Macbeth's castle to stay for the night. Macbeth and Lady Macbeth treat Duncan with respect and affection, doing all that is within their power to make him comfortable under their roof. Duncan believes they are his dear friends and loyal subjects. He does not realize that he will not live through the night, but the audience knows that Macbeth and his wife will murder him in his sleep within a few hours. This dramatic irony makes the dialog in the scene especially meaningful, sometimes disturbing and sometimes poignant because Duncan is so trusting.