Banquo.
Macbeth killed King Duncan after hearing the witches' prophecies and being urged on by his wife, Lady Macbeth
Macbeth is startled when the witches give him their prophecies of his future. However, they did not tell him how to accomplish these prophecies, so he madly and erratically takes things into his own hands with the help of Lady Macbeth.
Macbeth wrote Lady Macbeth a letter describing his encounter with the witches. Lady Macbeth reads it out at the beginning of Act I Scene 5
Macbeth's first reaction is to dismiss the prophecies out of hand, as would any sane person. However, the grain of truth, and his own ambition, are what lead him to wonder, though not necessarily believe, the prophecies to be true. It can be argued that it is not his reaction to the prophecies which is important, but that of his wife. Lady Macbeth, who does not hesitate to believe the prophecies, is the one to spur her husband into the actions that follow, and lead to his eventual downfall.
In Act 1, Scene 5 of Shakespeare's play "Macbeth," Macbeth does not creep into Lady Macbeth's bedroom. Instead, Lady Macbeth receives Macbeth's letter informing her of the witches' prophecies. Their encounter in the play takes place in other locations within their castle.
She helps Macbeth out by tricking him into killing the king. :P
Lady Macbeth has revealed her part and Macbeth's in a number of murders. Imagine what Macbeth would do if he knew that someone had heard that confession and knew of his guilt. The Gentlewoman puts herself in terrible danger by repeating what she has heard.
He told her about the three prophecies that he has been told by the witches. Thane of Cawdor, Thane of Glamis, and King of Scotland.
The witches only gave Macbeth prophecies. It was his decision to do so after Lady Macbeth persuaded him. Although the witches' intentions was probably to cause this murder, the witches did not make Macbeth muder Duncan.
Banquo is skeptical of the witches' prophecies and warns Macbeth to be cautious of their potential for deception. He also expresses his concerns about Macbeth's intentions and the possible means he may resort to in order to fulfill the prophecies.
Lady Macbeth was also missing from the banquet table in the scene from Shakespeare's "Macbeth" where Banquo's ghost appears. Lady Macbeth excuses herself from the table, fainting in response to Macbeth's behavior and the appearance of Banquo's ghost.
she wants to kill duncan so her husband can get his spot