Between Harper Lee's To Kill a Mockingbird and John Steinbeck's The Grapes of Wrath, there are several themes both stories have in common, such as "hope," "class conflict," "fanaticism," and "the individual vs society."
In To Kill a Mockingbird, "fanaticism" would be synonymous with "prejudice," and "class conflict" would parallel "racial conflict." This answer refers to the theme of "the individual [man] vs society."
In To Kill a Mockingbird, the individual vs society is seen several times. Dolphus Raymond is a white landowner in Maycomb County. However, he lives with a black woman and they have several children. This is not well-received by his neighbors: individual vs society. Raymond carries around a brown sack with a bottle in it. Everyone thinks it has liquor in it. When the court case sickens Dill, Raymond offers the boy a drink, and though Scout worries, Dill calms her by announcing that it's nothing but "Coca-Cola."
When asked why he keeps up the pretense, Raymond explains that it gives the people in town a reason they can live with—something to blame his behavior on:
"…why do I pretend? Well, it's very simple," he said. "Some folks don't—like the way I live. Now I could say hell with 'em, I don't care if they don't like it. I do say I don't care if they don't like it, right enough…When I come to town…if I weave…and drink out of this sack, folks can say [he's] in the clutches of whiskey…He can't help himself, that's why he lives the way he does.
Tom Robinson has been accused of raping a white woman, and the town is ready to lynch him. A mob appears one night while Atticus is guarding the jail—a group of white men have arrived to carry out their own form of justice. This is man vs. society (for Atticus and Tom).
Atticus also has to deal with man vs society in that many of his neighbors and members of Maycomb censures him because he is defending a black man. Even Jem and Scout face the same difficulties with their classmates, family members and neighbors.
In The Grapes of Wrath, a story of migrant families traveling the country looking for work and the American Dream after the Stock Market Crash of 1929, the idea of the individual vs society is prevalent also.
Tom Joad who began the story watching out only for himself—and keeping his prison record a secret—changes throughout the novel until he decides to help others. By the end, Tom is...
...able to recognize the nature and needs of others, [especially regarding] migrant farm laborers in California.
Here the individual (Tom) decides to take on society (in a very big way) by uniting migrant workers.
Ma Joad, also, is a woman who is committed to fighting the pitfalls society places in her way and her family's way. She assumes a leadership role within her family, and does all she can to protect them. Whatever society throws at her, and there are plenty of hardships she has to face, she is strong and resilient.
Finally, we see man vs society in the case of Jim Casey, a Christ-like figure in the story. He has chosen to dedicate himself to helping others. When it looks as if Tom will be arrested for beating an officer of the law at the Hooverville, Jim takes the blame. He goes to jail instead of Tom. He later becomes an activist, "reappear[ing] as a strike leader and union organizer." For this, he is eventually killed. Both of these examples demonstrate Jim pitted against society.