Iago is the main antagonist in William Shakespeare's tragedy Othello. He is a manipulative and scheming character who plots to ruin Othello's life by manipulating him into believing his wife Desdemona is unfaithful. Iago is often considered one of Shakespeare's greatest villains due to his complex and multi-faceted personality. He is a master of deception and manipulation, using his skills to manipulate those around him and achieve his own ends.