There is one, overwhelmingly, apparent similarity in both Harper Lee's novel To Kill a Mockingbird and William Shakespeare's play The Merchant of Venice: prejudice.
Outside of the fact that each are different types of prejudices, they do both play very relevant and important parts in each of the texts.
In To Kill a Mockingbird, the prejudice depicted is one of racial prejudice. In The Merchant of Venice, the prejudice is that of a religious nature.
Support of the racial prejudice in Harper Lee's novel can be seen in both the societal view and, more so, in Bob Ewell's prejudice. For example, the prejudice of Maycomb is seen in a quote taken from Atticus (Chapters 9 and 23):
Why reasonable people go stark raving mad when anything involving a Negro comes up, is something I don't pretend to understand.
The one place where a man ought to get a square deal is in a courtroom, be he any color of the rainbow, but people have a way of carrying their resentments right into a jury box. As you grow older, you'll see white men cheat black men every day of your life.
An example regarding prejudice in The Merchant of Venice is found in Act III (scene i, lines 58-68). Here, Shylock is admitting that people only treat him as they do based upon the fact that he is Jewish. Shylock, trying to prove himself to be similar to those around him, states the following:
I am a Jew. Hath not a Jew eyes? Hath not a Jew hands,
organs, dimensions, senses, affections, passions; fed with the same
food, hurt with the same weapons, subject to the same diseases,
heal'd by the same means, warm'd and cool'd by the same winter
and summer, as a Christian is? If you prick us, do we not bleed? If
you tickle us, do we not laugh? If you poison us, do we not die?
And if you wrong us, do we not revenge? If we are like you in the
rest, we will resemble you in that.
In both texts, it is apparent that people are treated differently, or prejudiced against, based only on the color of their skin or their Religious ideology. Regardless, prejudice is very apparent in each.