Tom’s father, Pa Joad, loses the motivation to lead his family early in the story when he is unable to get work and provide for them as he had before. So, Tom becomes a leader within the family alongside his mother, Ma Joad. While Ma Joad is the matriarch that holds the family together, Tom does his part to help keep the family going as well. Tom is also looked up to by his younger brother, Al Joad, who believes Tom is tough and mysterious for having killed a man and gone to jail.

Tom builds the biggest relationship outside of his family with Jim Casy. Whereas Tom is intuitive and pragmatic, Casy is gentle and reflective. Together, the characters represent two aspects of humanity: action and philosophy.

At first, Tom feels that Jim Casy talks too much; he doesn’t understand much of what Jim Casy reflects on. As the story progresses, Tom begins to understand Casy’s philosophy. Tom learns to focus on the needs of all those around him instead of focusing solely on his own needs. He learns the importance of working for the benefit of the community rather than for his own interests, a theme that Steinbeck explores throughout Grapes of Wrath.

Near the beginning of The Grapes of Wrath, Ma Joad is on equal footing with Pa Joad. They lead the family together, as Pa Joad is confident in his abilities to help and support the family. However, as the novel progresses and things become steadily worse for the family, Pa Joad becomes unable to provide and recedes from the role of patriarch. Because of this, Ma Joad is left to lead and make decisions for the family.

An example of Ma’s leadership can be seen when Ma Joad lies to the border agent and to the family about Granma. She claims Granma is very sick, but Granma had actually already died. So, Ma’s lie ensured that the family got through the border and the desert without complications. Despite the tragedy of the situation, Ma Joad took advantage of it and helped the whole family. Ma Joad makes many hard decisions, and in the face of strife, she rises up to be a successful and tenacious character.

Casy left the church after becoming unsure of his Christian religious practices and beliefs. Casy feels that his heart is no longer in the Christian religion. He also struggles with his past actions, feeling that he acted hypocritically.

Despite having left the church, Casy's role within The Grapes of Wrath parallels that of the biblical Jesus Christ: from sharing the same initials to wandering alone in contemplation to making the ultimate sacrifice.

However, Casy’s religious theory is that humans on earth are truly divine. He claims that he doesn’t love Jesus, as he doesn’t “know nobody name’ Jesus.” Casy's morality is not binary; he doesn’t see people or things as black or white, good or bad. His theory lies in the gray area, accepting of all people and actions, seeing good and bad things as just “stuff people do.” Casy chooses to love people as they are, even if some are bad and sinful. Casy is a teacher and helper to many throughout The Grapes of Wrath, as he strives to help those who are less fortunate until his death.

Rosasharn actively understands childbearing, and as Steinbeck wrote, “all the world seems pregnant to her.” Because of this, Rosasharn is mainly focused on her unborn baby throughout the novel. Her actions are dictated by her desire to have a healthy baby, which is difficult given the hardships the Joads face. As a result, she is also representative of the hardships that pregnant women face as child bearers and future mothers.

Rosasharn is abandoned by her husband, Connie, leaving her with an incredible amount of responsibility. Connie’s desertion is also symbolic of the further degradation of her quality of life; the entire Joad family faces even greater suffering when they reach California, which was supposed to be a promised land for them. Rosasharn further feels her isolation and the weight of her responsibility when her brother Al is pushed to marry Aggie Wainwright. She again is reminded of the fact that her husband has left her, and laments having to bear her child alone. Rosasharn’s jealousy and sadness is a reaction to the burden of being a single mother, despite her love for her unborn child.

When Rosasharn gives birth, the baby is stillborn. This symbolizes the end of her dreams for a better life; she has no husband, no home, no money, and now no child. Her baby is wrapped in a blanket and sent down the river during a flood, as a bad storm renders her incapable of burying her child. Rosasharn had placed all of her energy into her unborn child throughout the novel; her selfishness, in which she focused on only herself and her future child, is now without basis. Having lost her baby, Rosasharn is, in a sense, free from the binds of motherhood but must cope with the significant hole left behind from the loss of her child.

Pa Joad, the patriarch of the family, initially represents traditional authority. However, as the family's journey progresses, Pa struggles with the loss of his role and the harsh realities of their situation. His inability to secure work in California highlights the shifting familial dynamics, with Ma taking on a more decisive leadership role. Despite his waning influence, Pa remains a figure of dependability, his common sense and steadfastness providing a counterbalance to the more volatile characters around him.

Uncle John Joad is Pa Joad’s older brother. He lives alone and is viewed as a little wild. Uncle John was happily married in his youth. However, when his wife got sick, he didn’t call for a doctor. After she died from what turned out to be appendicitis, Uncle John blamed himself. He became strange, reclusive, and wild.

Uncle John tends to wander and is found in odd situations. Tom claims that each year only makes Uncle John “stringier and meaner.” Although he is viewed as a nuisance with his odd, paranoid behavior, Uncle John is very generous, and gave the Joad children gifts as they grew up. The Joad family initially resides at Uncle John’s farm after being kicked off their land.

Al is the second-youngest son of the Joad family. He looks up to Tom and tries to act like him. He both admires and fears Tom's having killed a man and spent time in prison. Al is only a teenager, but because he excels at fixing cars, the family allows him to be responsible for caring for the car and for driving it. Near the end of the novel, after having faced many hardships, the Joad family ends up staying in boxcars. While living in the boxcar, Al meets Aggie Wainwright, the daughter of the family the Joads share a boxcar with. Al is pushed to marry Aggie Wainwright after going on several dates with her.

Noah is the eldest son of the Joad family. He is calm and introspective, often reflecting on his surroundings. He never gets angry and is unable to understand why people feel that emotion. He rarely speaks, and when he does, he speaks slowly. Noah is intelligent and capable, but he is listless in nature and his appearance is described as slightly misshapen. When Ma was giving birth to Noah, Pa panicked and pulled on him, changing his head and body shape. Pa is ashamed of this and hasn’t told anyone, but he treats Noah nicer than the others as a result. Noah is with the Joad family when they begin their road trip, but when they stop before the California border at the Colorado River, Noah decides that he wants to stay and live by the river. He believes that he won’t starve if he stays by the river. Tom is unable to convince him to stay with the family, and Noah leaves.

Granma and Grampa Joad serve as embodiments of the older generation, deeply rooted in their land and traditions. Grampa, a vibrant, mischievous figure, resists leaving Oklahoma and ultimately passes away early in the journey, unable to adapt to the new life. Granma, fiercely religious and equally tenacious, survives longer but succumbs during the desert crossing. Their deaths symbolize the inevitable passing of the old ways, with Ma Joad carrying Granma's body to ensure their entry into California, highlighting her pragmatic leadership.

Ruthie and Winfield, the youngest Joad children, embody the innocence and potential of youth amidst adversity. Ruthie's brashness and Winfield's playful nature serve as reminders of the normalcy disrupted by their circumstances. Ruthie's inadvertent revelation of Tom's actions illustrates the fragility of their situation and the unintended consequences of youthful indiscretion.

Floyd Knowles is a migrant worker whom Tom and Al meet at a camp in California. Floyd wants to guarantee wages for himself and other destitute workers. When a contractor comes to the camp and tells the men that there’s work in the next county, Floyd is skeptical. Since Floyd knows that it’s illegal for a contractor to recruit workers without a license, he asks the contractor for a license to prove that there are proper wages. The contractor doesn’t show a license and claims that Floyd is a “red” and a troublemaker. When the deputy joins the discussion, he decides that Floyd is a criminal and tries to arrest him. Floyd punches him and runs away. Floyd is saved from being shot and jailed when Jim Casy kicks the cop in the neck. Jim Casy then goes to jail in Floyd’s place.

Muley Graves is one of the Joad family’s neighbors in Oklahoma. Graves, described as lonesome and coyote-like, is small, quick, and suspicious. Graves finds Tom Joad and Jim Casy in the beginning of the novel at the abandoned Joad family home. He explains to the two men where the Joad family went and updates them on what has been happening to the families and land. Although almost everyone is leaving to go west, Graves refuses to leave Oklahoma.

Graves is passionate about his land and home, claiming that he’ll kill some of the landowners if they try to kill him. Tom and Casy consider his refusal to go west as insane. Graves is stubborn, and he feels that he can’t leave his land just because he’s told to; he only would have left Oklahoma if he could have made the choice himself.

Connie Rivers is the young, nineteen-year-old husband of Rosasharn. He is good and hard-working, and he and Rosasharn are happy together. He is proud of Rosasharn but slightly fearful of her since her personality changed once she became pregnant. Connie becomes disappointed once the family is in California, because they have found few job opportunities. Connie is unable to handle the pressure when Rosasharn tells him that they need to have a house before the child is born. Connie claims that he’ll buy her a house after he starts earning money. He then leaves. After Connie has been gone for a while, the Joad family decides to leave the camp. Rosasharn is convinced he’ll return and wants to wait instead of moving again. Tom and Ma convince her that Connie will find them later. The family leaves, and Connie never returns to Rosasharn.

Ivy and Sairy Wilson, a kind-hearted migrant couple, join the Joads early in their journey. Their camaraderie and mutual support epitomize the communal spirit necessary for survival. However, Sairy's declining health forces the Wilsons to part ways with the Joads, illustrating the physical and emotional toll of the migration.

Timothy and Wilkie Wallace, father and son, are migrant workers who assist Tom in finding employment. Their camaraderie highlights the solidarity among migrants and the necessity of mutual aid in navigating the economic hardships faced in California.

Ezra Huston, leader of the Central Committee at the Weedpatch camp, plays a crucial role in organizing and maintaining order within the migrant community. His leadership exemplifies the collective governance that empowers residents to manage their affairs and resist external threats.

Aggie Wainwright represents the possibility of new beginnings amidst uncertainty. Her relationship with Al Joad symbolizes the continuation of life and the hope for stability through familial connections, even in the face of adversity.

The Wainwrights, fellow migrants sharing a boxcar with the Joads, epitomize the communal bonds that form among families during their shared struggles. Their encouragement of Al and Aggie's relationship underscores the importance of unity and cooperation in overcoming hardships.

Willy Feeley, a former small farmer like the Joads; he takes a job driving a tractor over the land the Joads farmed.

Jessie Bullitt,

Ella Summers, and

Annie Littlefield, the ladies’ committee for Sanitary Unit Number Four of the government camp for migrant workers.

Thomas is a farmer and the boss of several migrant workers, including Timothy and Wilkie Wallace. He tells the Wallaces and Tom about how the Farmer Association and The Bank of the West have lowered wages for migrant workers. He also warns the men about a fight that will be staged at one of the camps’ dances. Because Thomas warns the Wallaces and Tom in advance, the local police force’s plans to clear out the camp fail.