There are many prejudices in the book To Kill a Mockingbird. While the most obvious is racism, there are several others. There is a great prejudice against the poorer families and the Ewells in particular. It is well known that Bob Ewell spends his days drinking while his family suffers from poverty. His children are often pitied or looked down on at school. While the Cunninghams aren't quite in the same position, Walter Cunningham is treated differently by his classmates because of his family's financial status.
A different example of prejudice is centered around the Radley family. There are so many rumors mixed with the facts of Boo Radley's crimes that the townspeople no longer know the truth. Boo is feared and thought to be a dangerous man. His family is often shunned and somewhat blamed for Boo's alleged behavior. The speculation of the townspeople leads to a type of prejudice against the Radley family.
The people of Maycomb tend to be prejudice against anything that doesn't fit in with their idea traditional and customary. People who step outside the box are ridiculed or ostracized.