The crossword solutions for the term CASSIO ADVERSARY are Iago (4 letters), ANON (4 letters), and OTHELLO (7 letters). Iago is a character in William Shakespeare's play OTHELLO, who is the main antagonist. He is a soldier who serves as OTHELLO's ancient, or trusted advisor. ANON is an abbreviation of the Latin phrase 'Anonymus', which means 'UNKNOWN'. OTHELLO is the protagonist of the play, and is a Moorish general in the Venetian army. He is manipulated by Iago into believing that his wife Desdemona is unfaithful. Cassio is a lieutenant in OTHELLO's army, and is also manipulated by Iago into becoming an adversary of OTHELLO.