The main antagonist in Shakespeare's Othello, Iago is the trusted advisor of Othello, having fought at his side for several years. Believing that Othello unfairly promoted Michael Cassio to lieutenant instead of himself, Iago plots to manipulate Othello into demoting Cassio, effectively bringing about the downfall of Othello, as well. Iago convinces Othello that his wife, Desdemona, is having an affair with Cassio. After Othello kills Desdemona, Iago's wife, Emilia, reveals Iago's deception to Othello. Iago kills Emilia in a fit of rage, and Cassio, the new authority in the wake of Othello's suicide, condemns Iago to imprisonment and torture as punishment for his crimes.