Why does Iago hate Othello?

Iago hates Othello for several reasons. The most immediate reason is professional jealousy: Othello promotes Cassio to lieutenant instead of Iago, even though Iago believes he is more qualified. The play repeatedly presents Iago as angry and resentful about being passed over for promotion. Iago also claims that he suspects Othello has had sex with his wife, Emilia. He admits that he is not even sure the rumor is true, but says he will act as if it is. His suspicion fuels his desire for revenge, even though it may only be an excuse for the hatred he already feels.

At the same time, Iago’s motives go beyond any single grievance. He enjoys manipulating people and creating chaos. Throughout the play, he takes pleasure in deceiving others, treating events as if he were directing them, and working to ruin Othello while advancing his own position. Iago’s hatred is never completely explained by one cause. The promotion, the rumor about Emilia, his ambition, and his delight in manipulation all contribute to his campaign against Othello. By the end of the play, even when asked why he did what he did, Iago refuses to explain himself, leaving part of his malice mysterious.