Racism can be defined as the belief that a person's race determines what kind of characteristics such a person would have, without considering any other factors. It is a form of prejudice or discrimination in instances where there is a belief that belonging to a specific race naturally implies such a person's superiority or inferiority. 

In both Othello and The Crucible, this discrimination is directed at characters who are of a darker skin colour and are therefore seen as inferior or naturally inclined to do wrong. In Othello, the character who is a victim of this antagonism is our protagonist, general of the Venetian army. Although Iago does not say directly that he hates Othello for being a Moor, the remarks he makes about him, especially to Brabantio, Desdemona's father, clearly indicate his attitude. In Act 1, scene 1, he tells Brabantio:

'Zounds, sir, you're robb'd; for shame, put on
your gown;
Your heart is burst, you have lost half your soul;
Even now, now, very now, an old black ram
Is topping 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.

Iago's deliberate use of racial epithets in this extract plainly indicates his racism. His use of animal imagery in referring to Othello emphasizes the fact that he sees the general as less than human. Furthermore, the fact that he so specifically employs this kind of verbiage also suggests Brabantio's racism since Iago believes that Brabantio won't find such references offensive when they relate to Othello himself, but that he will definitely be disgusted about the fact that his daughter is apparently being abused by a man who is not only much older than her (more prejudice) but more specifically, that he is of a different race. 

Brabantio's racism is evident later when he uses similar references to Othello and unambiguously states that the general could not have won his daughter's heart without having used some foul method to do so. In Act 1, scene 2, he accuses Othello:

O thou foul thief, where hast thou stow'd my daughter?
Damn'd as thou art, thou hast enchanted her;...

...to incur a general mock,
Run from her guardage to the sooty bosom
Of such a thing as thou, to fear, not to delight.
Judge me the world, if 'tis not gross in sense
That thou hast practised on her with foul charms,
Abused her delicate youth with drugs or minerals
That weaken motion: I'll have't disputed on;...

Brabantio's prejudice is obvious. He accuses Othello of abducting Desdemona and using witchcraft in the process. He refers to  Othello as having a 'sooty bosom' and calls him a 'thing.' These terms convey his disgust. He, furthermore, refers to Othello using 'foul charms' and abusing her 'with drugs and minerals.' He wants a trial since he refuses to believe that Desdemona would have willingly eloped with the general. He continues in this vein when he later addresses the Duke of Venice in scene 3. 

Desdemona, however, clarifies the situation later when she defends Othello and testifies that she was a most willing partner in the elopement for she had fallen in love with him.

In The Crucible, Tituba, Reverend Parris' slave from Barbados is the victim of their racism. As a slave, Tituba obviously occupies a lowly position not only in the Parris household but also in Salem society - a clear enough indication of racial prejudice. At the beginning of the play, she becomes an easy target for Abigail's, Reverend Parris', Mr. Putnam's and even Reverend Hale's obvious prejudice. When Abigail blames her for encouraging them into performing illicit acts in the forest and summoning spirits, it is all too easy for them to take her word for it.

Since Tituba is clearly not educated and does not speak English that well, and therefore, cannot defend herself, her accusers and inquisitors easily assume that she must be guilty, even though she mentions that it was Abigail who begged her to conjure and make charms. Their racism is plainly evident in the manner in which they address and threaten her in Act One:

Hale: Woman, have you enlisted these children for the Devil? Tituba: No, no, sir, I don't truck with no Devil!
Hale: Why can she not wake? Are you silencing this child?
Tituba: I love me Betty!
Hale; You have sent your spirit out upon this child, have you not? Are you gathering souls for the Devil?
Abigail: She sends her spirit on me in church; she makes me laugh at prayer!

Hale, resolved now: Tituba, I want you to wake this child.
Tituba: I have no power on this child, sir.
Hale: You most certainly do, and you will free her from it now! When did you compact with the Devil?
Tituba: I don't compact with no Devil!
Parris: You will confess yourself or I will take you out and whip you to your death, Tituba!
Putnam: This woman must be hanged! She must be taken and hanged!

The poor woman is terrified and realises that her life is at risk. She decides to save herself by naming others. Her so-called confession implicates those she names and encourages Abigail to follow suit. She mentions the names of supposed witches who she testifies had visited her. Her admission leads to Betty's sudden revival and she also starts shouting out the names of people she had apparently seen with the devil. In the end, many are arrested and accused of witchcraft.