The main character Shakespeare presents in Othello to display the theme of jealousy is Othello himself and the impact jealousy has on him. Throughout Othello the theme of jealousy in the main character is presented as a poison, planted by Iago it spreads from a small idea to the cause of multiple deaths, destroying lives of even more. The first description of the jealousy soon to be planted on Othello is by Iago in Act 1 scene 3. He talks about Othello being "of a free and open nature," implying that this freedom won't last long, and explaining to the audience that he must "bring this monstrous birth to the world's light." The "monstrous birth" we can see is a reference to jealousy, Iago being the devil that gives birth to this one of the seven sins, envy. This monstrous birth is again refer to by Othello at the beginning of act 3 scene 3 as Othello becomes suspicious of Iago's rumors, questioning whether there is "some monster in thy (Iago's) thought too hideous to be shown." We think that Othello might see through Iago's tricks here but due to the obedient mask that Iago wears Othello plunges once again into ignorance. .
In the first few acts a very strong personality, both physically and mentally, of Othello is shown, firstly through his passionate speech to court to defend his right to be with Desdemona and in Desdemona's speech to Emilia after Othello's suspicions are aroused. In the fourth scene of Act 3 Desdemona is mildly distressed about the loss of her handkerchief but explains to Emilia and the audience that Othello "is true of mindmade of no such bareness as jealous creatures are." Questioning this in surprise, due to Iago's obvious jealousy of her and Cassio, Emilia asks "is he not jealous," as if this is a quality every man possesses. Desdemona explaining that "the sun drew all such humours from him" as if the blackness of his skin is sign of his immunity to jealousy's poison.