"O, beware, my lord, of jealousy; It is the green-ey'd monster, which doth mock The meat it feeds on." Othello Act 3, scene 3, 165–171 Jealousy is one of the most important theme in Othello. It is the reason why Iago is planning his revenge and what led to Othello's tragic end. Jealousy affects several characters such as Iago, Othello, Roderigo, Brabantio... Jealousy is often represented by the color green and in this quote is called 'the green-ey'd monster'