Tom Joad — Protagonist of the story; the Joad family's second son, named after his father. Later on, Tom takes leadership of the family even though he is young.
Ma Joad — matriarch. Practical and warm-spirited, she tries to hold the family together. Her given name is never learned; it is suggested that her maiden name was Hazlett.
Pa Joad — patriarch, also named Tom, age 50. Hardworking sharecropper and family man. Pa loses his place as leader of the family to his wife.
Uncle John Joad — Older brother of Pa Joad (Tom describes him as "a fella about 60", but the narrator later tells you he is 50), feels responsible for the death of his young wife years before when he ignored her pleas for a doctor because he thought she just had a stomachache, when she actually had a burst appendix. Filled with guilt, he is prone to binges involving alcohol and prostitutes, yet tries to repent for his sins and guilt by spoiling Ruthie and Winfield with candy when he can.
Jim Casy — A former preacher who lost his faith after fornicating with willing members of his church numerous times, and from his perception that religion has no solace or answer for the difficulties the people are experiencing. He is a Christ-like figure and is based on Ed Ricketts.
Al Joad — The second youngest son, a "smart-aleck sixteen-year-older" who cares mainly for cars and girls; looks up to Tom, but begins to find his own way.
Rose of Sharon Joad Rivers — Childish and dreamy teenage daughter (about 16 or 17) who develops as the novel progresses to become a mature woman. She symbolizes regrowth when she helps the starving stranger (see also Roman Charity, works of art based on the legend of a daughter as wet nurse to her dying father). Pregnant in the beginning of the novel, she delivers a stillborn baby, probably as a result of malnutrition. Her name is pronounced "Rosasharn" by the family.
Connie Rivers — Rose of Sharon's husband. Young and naive, he is overwhelmed by the responsibilities of marriage and impending fatherhood, and abandons her shortly after arriving in California. He is stated to be 19 years old upon his and Tom's first encounter before leaving for California.
Noah Joad — The oldest son who is the first to willingly leave the family, choosing to stay by the Colorado river and survive by fishing. Injured at birth, described as "strange", he may have slight learning difficulties.
Grampa Joad — Tom's grandfather, who expresses his strong desire to stay in Oklahoma. His full name is given as William James Joad. Grampa is drugged by his family with "soothin' syrup" to force him to leave, but dies in the evening of the first day on the road; Casy attributes his death to a stroke, but also says that Grampa is "jus' stayin' with the lan'. He couldn' leave it."
Granma Joad — The religious wife of Grampa Joad, she seems to lose the will to live (and consequently dies while crossing the desert, possibly as a result of exposure to the heat while crossing New Mexico and Arizona) after her husband's death.
Ruthie Joad — The youngest daughter, age twelve.
Winfield Joad — The youngest male in the family, aged ten. He and Ruthie are close.
Jim Rawley — Manages the camp at Weedpatch, he shows the Joads surprising favor.
Muley Graves – A neighbor of the Joads, he is invited to come along to California with them but refuses. Two of the family dogs are left in his care, while the third goes along with the family and is killed by a car on the road when they stop for gas.
Ivy and Sairy Wilson — Kansas folks in a similar predicament, who help attend the death of Grampa and subsequently share the traveling with the Joads as far as the California state line. It is implied Sairy is too ill to carry on.
Mr. Wainwright — The father of Aggie Wainwright and husband of Mrs. Wainwright. Worries over his daughter who is sixteen and in his words "growed up".
Mrs. Wainwright — Mother to Aggie Wainwright and wife to Mr. Wainwright. She helps deliver Rose of Sharon's stillborn baby with Ma.
Aggie Wainwright — Sixteen years of age. Daughter to Mr. and Mrs. Wainwright. Intends to marry Al. Aggie takes care of Ruthie and Winfield when Rose of Sharon goes into labor. She has limited interactions with the other characters. Her real name is Agnes.
Floyd Knowles — the man at the Hooverville who urges Tom and Casy to join labor organizations. He agitates the police and this results in Casy going to jail.
Joe/Mike – A deputy who is hit by Floyd, tripped by Tom and knocked out by Casy at the Hooverville. He claims that Casy did not hit him (as he did not see it) but Casy convinces him he did. He is called Joe by the man who he arrives at the Hooverville with to ask for peach pickers, but strangely the other deputies refer to him as Mike.
George – A guard at the peach orchard. He kills Casy, and is then killed by Tom.
Al - A waiter at a restaurant who orders Mae to give bread to a poor migrant family.
Mae - A waitress at a restaurant who is ordered to give bread to a migrant family. She later gives them two pieces of candy for one cent, when it is later revealed that the candy was a nickel apiece. She is then given an extra-large tip by truckers who ate lunch there.
Big Bill - A trucker who eats lunch at the restaurant where Al and Mae work. He and his friend, another trucker, leave an extra-large tip and then leave.