Why does Iago kill Roderigo?

In Othello, Iago kills Roderigo to keep his own schemes from being exposed. Throughout the play, Iago uses Roderigo as a source of money and as a pawn in his plots. Near the end, Iago persuades Roderigo to attack Cassio. When the attack goes wrong and both men are wounded, Iago realizes that Roderigo could reveal the truth about his manipulations. He therefore stabs and kills him to ensure that his secret won’t be revealed.

The play also shows that Iago views people mainly as tools. Earlier, he admits that he is using Roderigo for money while pursuing his revenge against Othello. By Act 5, Roderigo has become a liability rather than an asset. After Cassio wounds Roderigo, Iago kills him, then immediately tries to shift suspicion onto others, even accusing Bianca of involvement in the attack. 

Roderigo’s death highlights how completely Iago sacrifices anyone who might threaten him. He is willing to betray and murder even the man who has trusted and assisted him from the beginning of the play. The killing fits a larger pattern in Othello: Iago maintains power by controlling appearances, and anyone who might reveal reality becomes expendable.