While Duncan is asleep, Macbeth stabs him, despite his doubts and a number of supernatural portents, including a hallucination of a bloody dagger. He is so shaken that Lady Macbeth has to take charge of the assassination.

Overcome with guilt, Lady Macbeth tries to wash imaginary bloodstains from her hands.

Because of the witch's prophecy, Macbeth believes that he cannot be killed by any man born of a woman, but Macduff shatters Macbeth's last hope by revealing that he was "from his mother's womb untimely ripped".

In Act I, a wounded sergeant reports to King Duncan that his generals, Macbeth and Banquo, have just defeated the allied forces of Norway and Ireland, who were led by the traitorous Macdonwald, the Thane of Cawdor.

Macbeth says this when he and Banquo first discover the three witches.

At a banquet, Macbeth invites his lords and Lady Macbeth to a night of drinking and merriment. At first, Macbeth only sees that all the seats at the banquet are occupied. When Lennox calls his attention to the seat reserved for him, Macbeth realizes that Banquo's ghost is sitting in it.

Seyton is Macbeth's chief servant when his thanes are abandoning him. The fact that his name rhymes with "Satan" may be coincidental. He helps to arm Macbeth, and reports the Queen's death to him.

Lady Macbeth says this when she is trying to convince her husband to go through with the murder of King Duncan.

Hecate, queen of witches, is enraged that the main trio of witches have interfered with Macbeth without consulting her, particularly as she thinks very little of him.

Having discovered the body, Macduff wants to awaken the others and, ironically, even tries to protect "gentle" Lady Macbeth from the horror.