Final answer:
The quote "I shall remember. When Caesar says 'Do this,' it is performed" is from Shakespeare's play Julius Caesar. The character who said this quote is Marc Antony.
Step-by-step explanation:
The quote: "I shall remember. When Caesar says 'Do this,' it is performed" is from Shakespeare's play Julius Caesar. The character who said this quote is Marc Antony. In the play, Marc Antony gives a speech after the assassination of Caesar, in which he seeks to turn the Roman citizens against the conspirators.
The quote highlights Caesar's power and authority, as well as the obedience and loyalty of those who serve him.