Who King Duncan is
King Duncan rules Scotland, where Macbeth and Banquo serve him as generals against rebellion and invasion. He rewards Macbeth with the title of Thane of Cawdor after its previous holder is stripped of it for treason. For Macbeth, this reward also confirms part of the witches' prophecy that he will rise to become king.
Duncan is presented as a gentle ruler whose goodness Macbeth himself acknowledges. His trusting nature matters in a play that repeatedly separates outward appearances from hidden thoughts.
King Duncan and the others in the story
Duncan is Macbeth's king and cousin, and he becomes his guest when he visits the castle at Inverness. Macbeth recognizes each of these ties as a reason not to act against him. Meanwhile, Duncan names his son Malcolm as heir, making the succession an obstacle to Macbeth's hopes for the crown.
Questions
Who is King Duncan in Macbeth?
King Duncan is Scotland's ruler, served by the generals Macbeth and Banquo.
How is King Duncan related to Macbeth?
Duncan is Macbeth's cousin as well as his king.
Who does King Duncan choose as his heir?
Duncan chooses his son Malcolm to succeed him.