Othello, a Moor, serves as a general and commander of the Venetian armed forces and later becomes the governor of Cyprus. He secretly marries Desdemona, which triggers Iago's animosity when Othello promotes Cassio. Othello subsequently demotes Cassio, believing him responsible for initiating a drunken brawl. Gradually, Othello falls prey to Iago's scheming and, convinced of Desdemona's infidelity, smothers her. Upon realizing her innocence, he takes his own life.

Othello is a dignified and commanding figure, highly esteemed in his military career. At the play's outset, he experiences significant success and everything appears to be in his favor. Desdemona chooses him over her other Venetian suitors, and he successfully defends against Brabantio's accusations of coercion and abduction. The Duke of Venice and the Venetian senators appoint him to lead the forces defending Cyprus against the Turks. Upon arriving in Cyprus, Othello learns that a tempest has eradicated the Turkish threat. In Cyprus, Othello and Desdemona display their affection more openly and less formally than in Venice. They celebrate their marriage, and even the disruption caused by Cassio and Montano's brawl doesn't shake Othello's confidence and composure. Reflecting the archetype of the strong, heroic leader, he declares, "He that stirs next to carve for his own rage / Holds his soul light; he dies upon his motion" (II.iii.164-165). He is decisive and authoritative, ready to act without hesitation. However, Othello's self-assurance wanes as Iago begins to manipulate his thoughts, insinuating an affair between Desdemona and Cassio.

Initially, Othello dismisses the notion that his wife's grace, charm, and beauty could incite his jealousy, asserting, "she had eyes and chose me" (III.iii.189). But Iago's "medicine" (IV.i.46) soon takes effect, causing Othello to doubt Desdemona's continued love for him. When Iago suggests that Desdemona has already deceived her father and Othello, the Moor starts believing her betrayal is inevitable, considering his skin color, older age, and lack of refined manners (III.iii.263-268). He begins to act as if her unfaithfulness is a foregone conclusion, lamenting that "Othello's occupation is gone" (III.iii.357).

Iago stirs Othello into a jealous frenzy through numerous insinuations. However, it appears that the handkerchief—the one Othello originally gave to Desdemona as a token of love—is what finally drives Othello over the edge. Iago persuades Othello that the innocently dropped handkerchief was actually given to Cassio (who then passes it to Bianca) by Desdemona. Othello fixates on this piece of cloth as damning physical evidence during his confrontation with his wife. He references it repeatedly before killing Desdemona: "That handkerchief which I so loved and gave thee, / Thou gav'st to Cassio" (V.ii.48-49); "By heaven, I saw my handkerchief in 's hand" (V.ii.62); and again, "I saw the handkerchief" (V.ii.66). Despite Desdemona’s continuous denials of giving the handkerchief to Cassio, suggesting he might have found it somewhere, her protests are in vain.

Ultimately, Othello is so convinced by Iago's deception that he murders his wife in their bed. The most obvious reason for this act is the one Othello gives to Emilia, stated repeatedly in response to her persistent questioning, immediately after he has smothered Desdemona: "She turn'd to folly, and she was a whore"; "She was false as water"; "Cassio did top her" (V.ii.133; 135; 137). Othello believes Desdemona has betrayed him and their marriage, leading to her death.

Yet, some argue that Othello's motives are more profound, suggesting he killed Desdemona because she violated Venetian societal norms by marrying a Moor. Advocates of this perspective claim that Othello is accepted by Venetian society as long as he remains an external element. Barbantio and the Venetian senators are eager to benefit from his strength and military expertise, but when Othello integrates into their society through his marriage to Desdemona, his presence becomes disruptive. In his final speech, Othello asks to be remembered as "one that lov'd not wisely but too well" (V.ii.345). Is the object of that love Desdemona or Venice? Perhaps Othello never ceases to see himself as a soldier with the primary mission of safeguarding Venetian society. His last act—his own suicide—might be seen as a service to Venice, reflected in the language he uses to preface it. He instructs those around him to recount events exactly as they occurred,

And say besides, that in Aleppo once,
Where a malignant and turban'd Turk
Beat a Venetian and traduc'd the state,
I took by the throat the circumcised dog
And smote him—thus.
(V.ii.353-357)

The final word of this speech is punctuated by the sound of Othello's knife plunging into his chest, fatally wounding him.

In his final speech, Othello reflects on his life for future generations, describing himself as "one that loved not wisely but too well" (V.ii.345). However, from our perspective, Othello's self-evaluation misses the mark. He sees himself as an accomplished and worldly man, both in his own eyes and in the view of Venetian society. Not only has he gained extensive experience as a military leader, but he is also adept at sharing these experiences with others. Defending himself against Brabantio's accusations before the Duke, Othello recounts his initial interactions with Brabantio's daughter:

It was my hint to speak—such was my process;
And of the Cannibals that each other eat,
The Anthropophagi, and men whose heads
(Do grow) beneath their shoulders. These things to hear
Would Desdemona seriously incline:
But still the house affairs would draw her thence;
Which ever as she could with haste dispatch,
She'd come again, and with a greedy ear
Devour up my discourse.
(I.iii.142-150)

Even in Othello's brief, summarized mentions of the tales that form the foundation of his life, reputation, and social standing, there is a sense of wonder; we can almost hear the word "Anthropophagi" resonating from Othello's lips and picture those exotic beings with heads beneath their shoulders. In Act I, Othello seems assured of his own value. However, by the play's final act, Othello is utterly bewildered by what Desdemona's perceived infidelity implies about him as her husband. He struggles internally as he prepares to smother Desdemona in the play's climactic scene:

It is the cause, it is the cause, my soul,
Let me not name it to you, you chaste stars!
It is the cause. Yet I'll not shed her blood;
Nor scar that whiter skin of hers than snow,
And smooth as monumental alabaster.
Yet she must die, else she'll betray more men.
Put out the light, and then put out the light:
If I quench thee, thou flaming minister,
I can again thy former light restore,
(V.ii.1-9)

The turmoil Othello experiences at this moment is beyond his or our complete comprehension. Here, we witness Othello justifying Desdemona's murder as a means to preserve her honor, indicating that he has conflated her identity as his victim with his own role as both victim and perpetrator.

What stands out about Othello and partly explains his drastic fall from heroic leader to savage beast is how easily he is manipulated by Iago into self-destruction. Othello believes he understands Iago, but it is Iago who truly understands his superior and knows exactly how to manipulate him. For instance, Iago is aware that Othello's self-assured demeanor relies heavily on his esteemed reputation in Venetian society. Although this reputation is built on numerous military achievements, it can be tarnished. Additionally, Iago knows that Othello, who has spent most of his life on the battlefield, feels insecure in civil society and in his role as the governor of Cyprus. Ultimately, Othello is an outsider, a mercenary for Venice, wary of threats and suspicious of those who accept him, especially if his standing or esteem in their eyes changes.

There are two main interpretations of Othello's character that have emerged among students and critics: one that views him as virtuous, strong, and trusting; and another that sees him as guilty of self-idealization and excessive pride. Both perspectives are supported by the transformation in Othello's behavior. Initially, he is portrayed as a strong, confident character using typical heroic language. However, as he succumbs to jealousy and rage, he begins to resemble Iago, adopting the villain's animalistic and diabolical imagery. Critics who consider Othello essentially noble argue that this shift illustrates an innocent hero falling victim to Iago's schemes and being corrupted by his evil. On the other hand, some argue that Iago's actions merely expose Othello's inherent savagery, causing his noble facade to crumble. The first interpretation places most, if not all, of the responsibility for Othello's downfall on Iago, while the second places a significant portion of the blame on Othello himself.