There are several characters in To Kill a Mockingbird who are classic stereotypes. Bob Ewell is the most obvious example, representing "poor, white trash" of the worst kind. Bob has absolutely no redeeming qualities: He has no job, drinks up his welfare paycheck, is practically illiterate, pays no attention to his children's needs, and stirs up trouble wherever he lurks. He is the epitome of the racist white man in his lowest form.
The Cunningham family is another example of stereotyping. The Cunninghams are racist; it is Walter Sr. who leads the lynch mob that plans to hang Tom Robinson. But, as Jem points out in his "four kinds of people" in Maycomb social ladder, the Cunninghams are honest, hard-working people, farmers who are down on their luck--unlike Bob Ewell, who is too lazy to hold down a job. One of the Cunninghams even proves to be the lone holdout on the jury, a man who hates blacks but who also has a conscience.
Lula, the African-American woman who objects to Calpurnia bringing Jem and Scout to the all-black church, is a stereotype of a different sort. She is big, loud and forceful, and she tries to rally support among the congregation to bar Cal from entering the church with the white children. However, no one sides with her. Lula represents the small but emerging black voice that objects to the Jim Crow laws and white power social structure that continues to keep blacks on the lowest step of Maycomb's (and the Deep South's) social ladder.