Iago is a ‘liar, betrayer, mental torturer and murderer’.
His ‘ambition, spirit and intellectual activity’ leave audiences torn in their feelings towards him.
He is the play’s ‘chief humorist’ and has the most lines.
He ‘confides in us’ making the audience the ‘villain’s accomplices’.
Iago has ‘essential sadism’ with it ‘scarcely mattering who kills whom’ as it all fulfills his plot eventually.
He doesn’t understand ‘loyalty’ and ‘friendship’ despite his ‘cleverness’ so can’t comprehend Emilia’s betrayal of his plot.