Othello is presented as a strong, noble character who seriously falls victim to the machinations of Iago. Othello's faults become obvious late in the play, and they lead to a tragic fall for himself and many around him.
Early in the play, Othello seems known as a strong military leader who is respected by the men who know him and work with him. He is the general of the Venetian army and is apparently trusted by Venice's officials. We learn right away that Othello has eloped with Desdemona, the daughter of a Venetian noble. He explains to her father that she fell in love with him while listening to his stories of exotic adventures around the globe. Their marriage is the result of quick and passionate courtship.
Othello's character begins to change when Iago tries to trick him into believing Desdemona is cheating on Othello with Cassio. Othello shows himself to be naive and gullible, as well as excessively jealous. He quickly and fairly easily turns on his wife, based only on Iago's word. Othello angrily orders Cassio's murder and then kills Desdemona with his own hands. It is only after he kills her that he realizes he was misinformed and manipulated. Othello cannot deal with his actions and kills himself. The play suggests that Othello feels justified in punishing his wife for infidelity; it is only when he learns she was "chaste," as she said she was, that he feels guilty about the murder.
Othello's character ties into the themes of passion and jealousy. The play displays the dangers of passion and how it can both create and destroy. The marriage was a result of passion but so was its downfall. Othello's inherent jealousy is exacerbated by Iago's manipulation, and the play shows how envy has dangerous and even deadly consequences. As a tragedy, the play also demonstrates how a character who begins in a high position can be totally ruined by his tragic flaw.