"I know his gait, ’tis he.—Villain, thou diest!" (5.1.23)
"I am maimed forever. Help, ho! Murder! Murder!" (5.1.27)
"Oh, villain that I am!" (5.1.29)
"Oh, the more angel she, And you the blacker devil!" (5.2.135)
"She’s like a liar gone to burning hell!’Twas I that killed her" (5.2.133-134)
In the first scene of Act 5, Iago convinces Rodrigo to kill Cassio. Iago hopes that they both just kill each other and stays back to see what happens.
"O thou Othello, that was once so good,Fall’n in the practice of a cursèd slave" (5.2.299-300)
After Rodrigo fails to kill Cassio, Iago stabs Cassio in the back of his leg injuring him. He then proceeds to kill Rodrigo so he is not able to tell everyone what really happen. Since there are not witnesses to see Iago he leaves and later comes back when everyone comes to see what is happening.
In this scene when Emilia finds Desdemona dead, she compares Desdemona to an angel and Othello to a "blacker devil." This emphasizes how white folks were seen as angelic and the connotation with black was compared to evil, in this case the devil.
In the last scene of Othello, Lodovico and Montano enter and find out what has happened, Lodovico says that Othello was once good but has acted like a "cursed slave." This last scene, even after they find out Iago caused all this, they refer to Othello as a slave for acting this way. This continues to show the racism they held throughout the whole play.