Iago
Iago is Othello's most trusted man, by his side at crucial moments. Ironically, Iago seeks to bring down the great Moorish General even though he has pledged his loyalty to serve him.
Storm
Othello has gone to Cyprus in order to stop the Turkish invasion from coming any further. Ironically, when he and his fleet arrive the Turkish army has been wiped out by a massive storm and Othello and his men are able to return home unharmed.
Drunk
Iago convinces Cassio to get drunk even though the soldier knows he doesn't handle his liquor well. Ironically, Cassio gives in and it allows Iago's plan to split up Desdemona and Othello to begin to hatch.
Death of Love
Othello has just killed Desdemona for betraying him with Cassio. Ironically, just after her death Emilia reveals that she stole the handkerchief for Iago, and Othello realizes he's killed his wife who was completely innocent.
Accused
Othello accuses Desdemona of losing his mother's handkerchief, actually he believes she's given it to Cassio as a token of her love. Ironically, Emilia has stolen it for Iago who's placed it with Cassio in order to get Othello to kill Desdemona.