There are prime examples of stereotyping in Harper Lee's To Kill A Mockingbird from some of the more important characters in terms of the plot like Tom Robinson and the Ewells, Miss Crawford, the local gossip, and the unfriendly Mr. Radley. Unfortunately, as with real-life situations, some people live up to the expectations of others and are destined to fail due to their circumstances and own outlook (such as Bob Ewell). Some live up to the stereotype and their actions or behavior may be offensive but are not intended to cause harm (such as Miss Crawford), and others affected by stereotyping suffer because it is society which prevents them from rising above the prejudice (Tom Robinson is a good example of this).
Maycomb County is a town where the residents have strong and mostly toxic opinions which Atticus politely terms "blind spots" (chapter 16) and where words like fairness, justice and impartiality can ironically only be applied after first giving consideration to the person being judged and whether he or she in fact qualifies for fair treatment, justice and so on. For example, in Maycomb, black people are not subject to the same law as white people. The Ewells, particularly Bob Ewell, who is well-known as a drunk and abusive father, and who is considered white "trash," are deemed as telling the truth in preference to honest, hard-working Tom Robinson simply on the grounds of skin color.
The people of Maycomb would justify their actions by blaming Tom for fraternizing with a white woman in the first place! In his defence of Tom, Atticus says that Mayella is trying to hide the fact that she has "broken a rigid and time-honored code of our society, a code so severe that whoever breaks it is hounded from our midst as unfit to live with..." (chapter 20). The stereotype, evident in the so-called "code" which Mayella has broken and which has shamed her father (ironically), is looking for affection from a black man.
In chapter 1, Scout exposes the stereotypical female Maycomb residents who "bathed before noon... and by nightfall were like soft teacakes with frostings of sweat and sweet talcum." Aunt Alexandra is a stereotypical female who fits into Maycomb society; she constantly worries about Scout, who she does not think behaves appropriately like a young lady should. In chapter 8, Scout tells the reader that "Aunt Alexander's vision of my deportment involved playing with small stoves, tea sets, and wearing the Add-A-Pearl necklace..." As a tomboy, this image does not impress Scout at all; she is happy in her "breeches."
"Boo was about six-and-a-half feet tall, judging from his tracks; he dined on raw squirrels and any cats he could catch, that's why his hands were bloodstained -- if you ate an animal raw, you could never wash the blood off. There was a long jagged scar that ran across his face; what teeth he had were yelow and rotten. his eyes popped, and he drooled most of the time."
This quote shows the impressions the neighbors have of Boo Radley. Because he locks himself in his house and never comes out, the neighbors immediately stereotype him as a monster. The words "judging from his tracks" show the stereotyping; the neighbors judge his actions instead of getting to know him. In reality, Boo Radley is actually very kind and gentle.
Other themes that relate to stereotyping that you could pull quotes out of include race and gender.