Othello, by William Shakespeare, is a play demonstrating that we all have strengths and weaknesses and that while the best of us will focus on people's strengths, the worst of us will not only not weaknesses but use them in destructive ways. Throughout the play, the weakness of jealousy, directly or indirectly, brings the destruction and downfall of all the major characters, including not only Othello and his bride Desdemona, but Iago, his wife Emilia, Roderigo and Cassio.
Othello is particularly vulnerable because, being a Moor, he is somewhat an outsider (Weller, PAGE). He is accepted as a leader in society and as a great military man, but he is aware of his differences. He used them to charm those around him, wooing and winning the beautiful Desdemona and then defending her marriage to others, but the villain of the play, Iago, knows that it can be easy to cast doubt on an outsider, and he uses Othello's differences to his own perverted and personal advantage.
While the name of the play is Othello, any discussion of jealousy in the play must start with Iago, because he is the one who sees the opportunities to foment jealous in the other characters. His motivation seems to be jealousy as well although it's difficult to know exactly why Iago is jealous of Othello.
First he claims to be angry because Othello passed him over for a promotion (I.i, 7-32). In the second scene he goes further, suggesting that Othello slept with his wife Emilia, Desdemona's maid. He says,
It is thought abroad that 'twixt my sheets / He has done my office" (I.iii.369-370). By "abroad" he means it is widely known, and by "office" he means having sex with Emilia (Weller, PAGE). However, he later admits that he knows it isn't true, but mentions it again later, making viewers think that maybe he does believe it. He says he wants to sleep with Desdemona to get even with him "wife for wife" (II.i.286) and is one reason he decides to make Othello jealous (Weller, PAGE).
Perhaps what Iago is really jealous of, however, is Othello's power. Having been passed over for a promotion, he imagines Othello sleeping with his wife, a loss of power, and then imagines sleeping with Desdemona, a restoration of power, and seems to enjoy the revenge he vents on others. All of his intrigues give him great power over others.
Iago is at his most manipulative as he curries Othello's trust. In the second act, Iago states it clearly, bragging that he will "Make the Moor thank me, love me and reward me. / For making him egregiously an ass" (2.1, 308-309). Iago is all too successful.
When Othello demands "ocular proof" (evidence he can see with his own eyes) of Desdemona's infidelity, Iago claims that Cassio has "wiped his beard (III.iii.444) with the handkerchief Othello gave her. Othello believes the planted evidence of Desdemona's supposed infidelity, and kills her in a jealous rage, and once he realizes his mistake, kills himself.
Desdemona pays the final price for other people's jealousies. She maintains her dignity to the end, even forgiving her husband, but Othello does not realize he was mistaken about her until it is too late.
Cassio is ruthlessly used by Iago. Iago makes sure that Cassio loses his promotion to lieutenant, and places the idea in the minds of other people that Desdemona might choose him as a sexual partner. Thus when Iago plants Desdemona's handkerchief in Cassio's quarters, it is easy for others to believe that Desdemona has been there. Cassio is destroyed by jealousy indirectly, by being manipulated into playing a role he would have otherwise wanted no part of.
Iago uses Roderico's longing for Desdemona to cast doubt on her. He assures Roderico that Desdemona will soon stray and seek another sexual partner (II.i.222)m but then suggests that she would choose Cassio over him, thus maneuvering the gullible and love-sick Roderico into his plot to set Cassio and Desdemona up.
Emilia, Iago's wife and Desdemona's maid, is used by her husband although she eventually sees through him, to her downfall. Iago convinces her to take a special handkerchief from Desdemona, which he uses as false evidence against Desdemona and Cassio later to humiliate Othello. Too late she realizes how her husband used the handkerchief, and Iago kills her.
The only one of the main characters who doesn't die is the person with the most responsibility for…