Iago does not exist
He's the incarnation of that voice within every person's mind, which is why it's so easy for him to trick everyone into believing what he says. He's not saying it — they're thinking it. Emilia is just a klepto with self-esteem issues; Othello is suffering from paranoia (or, if you hold that his seizures are real, he's also having epileptic hallucinations); Roderigo is generally unstable; Cassio has a serious drinking problem... the list goes on. Iago is just an excuse for their own bad behaviour. Killing Desdemona effectively snaps our hero out of this funk, leading him to kill Iago and thus free himself from the toxic influence of his own self-hatred. Of course, all he manages to do is convert it into soul-crushing angst (Emilia in her death scene) that makes him take his own life to 'follow' his lover, but still.- Othello doesn't kill Iago though. He only lightly wounds him.
Othello suffers from MPD, and Iago is the other personality.
Since the story is told mostly from Iago's point of view, the whole thing is a severe case of Unreliable Narrator. Everyone in Othello is in the psych ward.
Iago started out as a delusion of one of the patients; the rest ran with it, editing him into their own personal safety net. "As long as it's Iago's fault, it's not mine." When each of the characters 'die' in the story, they've been released — either cured or on their way to recovery. Othello is released when he kills 'his' Iago.- Uhhhh, guys. Iago never died. He was captured, and it's strongly suggested he'll be tortured.
Iago did die.
This is made explicit in the Laurence Fishburne version of Othello (in which Kenneth Branagh plays Iago.)- Except not really; he doesn't die onscreen, and it's never clearly shown whose bodies are dumped into the ocean. It could just as easily be Desdemona and Othello being tossed overboard.
Othello is a story about sexual impotence and the blue balls.
Othello and Desdemona are off to Cyprus to consummate their recent marriage, and on the big night they must have been interrupted by Cassio's fight. For the rest of the play, Othello does not get another opportunity (it is safe to guess he hasn't ever had sex with Desdemona), and during the whole time he is being constantly reminded that Cassio has been getting the goods. Throughout the play, Iago is constantly bringing up sexual imagery, and feeding into Othello's feelings of sexual inadequacy. Othello's feelings of betrayal are exaggerated by a sexual longing that goes unfulfilled. It can't be an accident that the place he chooses to murder her is in the marriage bed.
- Well he doesn't really choose it. Iago suggested that location. But I suppose that's neither here nor there.
- Iago makes derogatory statements about Moors and women, and, while he is undoubtedly sexist and racist, part of it is that his jealousy of Othello's life makes him double down more on the bigoted comments than usual. He knows Othello loves Desdemona, and Iago's own wedded life is in shambles, so he explicitly sows seeds of doubt in Othello's mind about Desdemona's faithfulness in particular. He personally believes he deserves Othello's position more than him, and knows Othello is conscious of his race, and explicitly pokes at that insecurity. Everything Iago tries to ruin about Othello's life is based in insecurities Iago himself has already. His true goal is to drag Othello to his level, which is why he never discusses his true motive; if he did, it'd mean baring his own insecurities for others to see, and a narcissist like Iago would hate that type of heart-baring.
