Iago is one of the most notorious and mysterious villains of all time. He spends all of his time plotting against Othello and Desdemona, eventually convincing Othello that his wife has been cheating, despite the fact that Desdemona has been completely faithful.
Iago's capacity for cruelty seems limitless, and no motivation that he gives for his actions seems enough to explain for the incredible destruction he wreaks on the lives of people he knows best.
Iago is an artist of evil. The same way that some people enjoy writing songs or filming movies, Iago enjoys ruining people's minds.
He does it with a sense of craftsmanship, appreciating the elegance or cleverness of a particular step in his scheme as much as its final result: incredible suffering for the people he has chosen. Ever notice how he stops every time he does something cleverly evil, to muse on it and tell…