Iago is a manipulative and secretive villain in Othello. He uses others' weaknesses to achieve his own goals, convinced that the ends justify the means. Iago manipulates characters like Roderigo, Othello, and Cassio by exploiting their lust, jealousy, and sense of honor. He hides his true nature and motives behind a mask of honesty while sowing seeds of doubt, destruction, and revenge. Iago's lack of morals is shown through his lies, manipulation of others, and refusal to show remorse for his actions in the end.