King Duncan is a fictional character from William Shakespeare’s Macbeth. He is a rather stupid man who creates dramatic, verbal, and situational irony through his trusting nature. Upon arriving at Dunsinane, Macbeth’s castle, he announces that: “this castle has a pleasant air.” In fact, the inhabitants of the castle are planning to kill him and steal his crown.

He is particularly gullible since he has been hoodwinked before by MacDonwald, the traitor who Macbeth kills. When Macbeth kills him, he inherets his position. Since clothing is a symbol for social status in Macbeth, it is telling that Macbeth calls these honours "borrowed robes."

After MacDonwald's betrayal, Duncan tells Macbeth: “There is no art to find the mind’s construction in the face. He (MacDonwald) was a gentleman in whom I placed an absolute trust.” After this verbally ironic phrase, Duncan places an absolute trust in Macbeth, who kills him.