Final answer:
King James I is supposedly descended from Banquo in Macbeth.
Step-by-step explanation:
In Macbeth, King James I is supposedly descended from Banquo. In the play, the witches tell Macbeth that he will be king, but they also tell Banquo that his descendants will be kings. This implies that Banquo's descendants, including King James I, would inherit the throne.