Minor characters in any literary work often serve as foils to the main characters; that is, in the presentation of their characteristics, the lack of these particular characteristics in the main characters becomes more apparent to the readers/audience. In addition, minor characters' actions and words can help to advance the plot or develop themes of a literary work.
- Portia, the wife of Brutus, is like Caesar's wife, Calpurnia, in that she wishes to share in the life of her husband and is concerned for his welfare. Both Portia and Calpurnia are intuitive and sense the danger that surround their husbands. Caplurnia's good sense points to Caesar's subverting his to his ego when he learns that he will be exalted if he goes to the Senate on the Ides of March. And, if Brutus were to have told Portia his "counsels" as she begs, he may have not made his tragic mistake of slaying Caesar. These women are foils to the men.
- Artemidorous is a friend of Caesar's who tries to warn him about Brutus and the other conspirators. He stands in the street near the Capitol near the house of Brutus, hoping to give his letter to Caesar. When he does place it in Caesar's hands, he tells Caesar it is a matter of personal reasons. Because the letter is personal, Caesar fatefully postpones its reading. The character of Artemidorous acts as a foil also, pointing to the unsound judgment of Caesar, thus, also, advancing the plot of assassination.
- Lucius is a servant to Brutus who delivers letters forged by Cassius highlighting Caesar's alleged ambitions. Clearly, he serves to advance the plot.
- Titinius is a friend of Brutus and Cassius. In Act V he approaches nearby troops in order to learn if they are friends or enemies. When he is surrounded on his horse by cheers and cries, Cassius's bondsman, Pindarus, hears them and mistakenly interprets them as meaning that Titinius is captured. Fearing that he will also be captured, Cassius takes his own life. When Titinius returns and sees his friend slain, he mourns the end of Rome as he has known it and crowns the dead Cassius with a wreath, and then kills himself. Titinius advances the plot and also points to the trope of the tragedy of miscommunication that prevails throughout the play.