In the Shakespearean play Othello, the main bad guy is named Iago. He pretends to be Othello’s closest friend, offering counsel and advice, but all the while he’s plotting his friend’s downfall behind the scenes. The play is carefully constructed so that it’s impossible for even the audience to grasp the underhanded deceit of Iago until the very last scene. He’s plausible right up until the end, and if his part is acted well, the audience will often gasp when his true nature is finally revealed, for the character’s deception is convincingly hidden by his words and actions.