Iago is a fictional character in Shakespeare's Othello. Iago, one of Othello's best friends, spends most of the play attempting to bring about Othello's downfall out of jealousy. He eventually does destroy Othello's reputation (which leads the Moor to kill himself), but sets the stage to his own doom when his wife Emilia reveals the whole of his plot. At the end of the play Iago is ordered imprisoned and executed by Cassio, Othello's chief lieutenant.

Iago is one of Shakespeare's most sinister villains. Shakespeare contrasts Iago with Othello's nobility and integrity of character. He has more lines in the play than Othello does - the most any of Shakespeare's non-title characters has.

Iago fits into the character type of the malcontent because of his bitter and cynical view of what he sees in the play.

While the play suggests motives for Iago's hateful scheming, many readers feel that a deeper root remains hidden. Iago cites suspicion that his wife has been unfaithful to him with Othello or bitterness that Othello passed him up for a big promotion. Whatever his deepest motivation, his hatred towards the Moor is unwavering and moves the action of the play forward. Some modern directors interpret Iago's hate as racism.

The role of Iago has been played in theatre by many famous film stars, such as Ian McKellen, Christopher Plummer, Laurence Olivier and Kenneth Branagh.

Iago is also a character in Walt Disney's Aladdin, a talking parrot who served as a sidekick for Jafar. Iago later switched sides in the movie sequels and television series. However, he is still largely conniving, rude, and greedy. In addition to being able to speak English, Iago has the ability to perfectly mimic other characters' voices. He is voiced in both film and TV series by Gilbert Gottfried.