because of the too many characters in the play, I suggest you study the major characters and their roles first, as it will help you easily identify them in play 

1. Othello: A Moorish general in the Venetian army. Respected for his military skill but faces racial prejudice.

Passionately in love with Desdemona but easily manipulated.

2. Iago (The Villain)

Othello’s ensign (or flag or standard-bearer).

He is the one causing the whole problems in play 

3. Desdemona (The daughter of the Senator-brabantio) she is Othello's wife 

4. Cassio: Othello’s second in command in the army.

5. Emilia (Iago's wife ) and a servant to the Desdemona

6. Roderigo, he's A wealthy Venetian who loves Desdemona but couldn't get her

7. Brabantio, a senator and the father of Desdemona 

8. Bianca (The Jealous Mistress)