In William Shakespeare’s Othello, Iago is the manipulator of the play and makes many acts of cruelty which eventually reveals his true side of evil and jealousy.  “I am not what I am,” is the self-assessment of Iago. Here Iago states that he will not be his true self and will do anything to take revenge on Othello. He will manipulate his best friends for him to get what he wants. Iago is also very jealous and racist towards Othello which drives him to hurt people just so he can win. 
Jealousy is played out throughout every character in this play, but Iago shows this in many ways and also proves that it drives him to hurt more. Jealousy sometimes makes him slip a couple of words; it makes his rage uncontrollable it makes him desperate for revenge. Iago eventually reveals his true side of evil and jealousy, after killing Cassio, his best friend Roderigo, and making Othello kill his wife. Iago is jealous of Cassio as Othello chose him over Iago for lieutenancy. This is the biggest reason for where all his jealousy started. 
Manipulation is Iago's specialty and has learned how to manipulate basically everyone. He manages to manipulate Othello into thinking that his wife is cheating on him. Iago makes Othello his little puppet, every little thing that Iago wants him to do he will do. Because Othello thinks that Iago is his best friend, he believes that he can trust Iago better than anyone else. Iago managed to manipulate Othello just by creating one false statement. Iago is so careless of people that he managed to take Othello by advantage and make him his dog. This is why he tries to hide his cruelty, by hurting everyone. 
Racism is also a major thing in Othello, because Othello who is the general was black, which is why so many people would call him the moor when talking bad about him, because it’s a racist name that they would call black people. Everyone was Venetian and he was the only black person. This increased the possibility for Iago to manipulate him, because he would say things like “Even now, now, very now, an old black ram Is tupping your white ewe. Arise, arise! 
Awake the snorting citizens with the bell, Or else the devil will make a grandsire of you. Arise, I say! (1.1.97-101),” and would get further into Othello's mind and start making Othello jealous. Racism was one of the ways that Iago would hide his cruelty he would say racist claims behind his back, and plan things against him while still making Othello think he is his friend. 
In conclusion, Othello by William Shakespeare reveals, through Iago, the depths of human evil. Because of Othello's favoritism of Cassio, he is driven by jealously to harm and manipulate other people. Othello becomes a puppet under Iago's clever manipulation, taking advantage of their "friendship". Racism makes him more cruel, since it takes use of Othello's race to create jealousy and gradually control him. This drama leaves the audience with a strong idea of human nature by showing how jealousy, manipulation, and racism can ruin even the closest relationships.