Protag.. I mean Antagonist

The antagonist in Othello is clearly Iago. He has started all the drama that has gone down so far. He has many different faces and is driven by pure jealously. He treats his wife like dirt.. "A good wench. Give it to me" (III.iii.314) (And yet she continues to obey him). He's an overall terrible character.

I can't identify with proof the protagonist yet, but I'm guessing it is Othello.

Cassio and Iago are probably foil characters. Cassio has been actually doing his job and cares about his reputation through actual hard work. (He does his job) and Iago is only looking out for himself and his own reputation and is willing to take out anyone in his way of becoming second in command under Othello.