Answer:
Banquo.
Explanation:
William Shakespeare's Macbeth tells the tragic story of how the protagonist Macbeth brought his own ruin by being over-ambitious. He, along with his wife Lady Macbeth, used force and even illegal and traitorous deeds to get their wishes to come true.
In Act V scene i, the doctor was summoned by the gentlewoman who had reported that her mistress has been sleepwalking for some nights now. Once when both of them observed Lady Macbeth sleepwalk again, they heard her say "who would have thought the old man to have had so much blood in him." This "old man" that she mentioned is Banquo, whom she had just murdered so that the three witches' prophecy about her husband might come true.
