For other uses of the name Duncan, see Duncan (disambiguation).

In William Shakespeare's Macbeth, Duncan was the King of Scotland. In the play, Duncan is killed by his cousin and trusted captain, Macbeth, at the insistence of Lady Macbeth.

An unnamed actor in the Karidian Company portrayed the elderly King Duncan when the acting troupe performed Macbeth in 2266. (TOS: "The Conscience of the King")