You may often hear or see Iago being referred to as Othello's "ensign." An ensign is sometimes also referred to as a "standard-bearer." In either case, Iago serves as a military officer, "a man of...of loyalty and trust" to Othello's face, but he turns out to be a villain and an "inhuman dog" who is egotistical and evil.
Iago may not die onstage, but his doom is certain. In the play's final lines (5.2.377-381), Lodovico directs Cassio, in his first assignment as the lord governor:
...To you, Lord Governor
Remains the censure of this hellish villain.
This time, the place, the torture, O, enforce it!
Myself will straight aboard, and to the state
This heavy act with heart relate.