Final answer:
There is not a single speaker in Shakespeare's Macbeth; characters like Macbeth, Lady Macbeth, and others contribute dialogue throughout the play, so the speaker cannot be determined without additional context.
Step-by-step explanation:
In William Shakespeare's play Macbeth, the "speaker" can refer to any character who delivers lines of dialogue. Throughout the play, there are numerous speakers including Macbeth himself, Lady Macbeth, King Duncan, the witches, and other characters. Each scene features different characters speaking to each other or delivering soliloquies. The provided excerpts from the play include speeches by characters such as First Witch, Macbeth, Banquo, Lady Macbeth, and Macduff, which implies that there is not a single speaker throughout the entirety of the play. Depending on the context of the question, if it refers to a specific excerpt, the speaker may be determined; otherwise, it cannot be determined without additional information.