Joe Keller — Joe, 60, was exonerated after being charged with knowingly shipping damaged aircraft engine cylinder heads (for P-40s) from his factory during WWII, causing the deaths of twenty-one pilots. For three and a half years he has placed the blame on his partner and former neighbor, Steve Deever. When the truth comes out, Joe justifies his actions by claiming that he did it for his family. At the end of the play he commits suicide in a sad attempt to rid his family of the problems he has caused them and perhaps also to stop Kate from hating him.
Kate Keller (Mother) — Kate knows that Joe is guilty but lives in denial while mourning for her older son Larry, who has been MIA for three years. She refuses to believe that Larry is dead and maintains that Ann Deever — who returns for a visit at the request of Larry's brother Chris — is still "Larry's girl" and also believes that he is coming back.
Chris Keller — Chris, 32, returned home from World War II two years before the play begins, disturbed by the realization that the world was continuing as if nothing had happened. He has summoned Ann Deever to the Keller house in order to ask her hand in marriage, but they're faced with the obstacle of Kate's unreasonable conviction that Larry will someday return. Chris's idolization of his father results in his devastation when he finds out the truth about what Joe did.
Ann Deever — Ann, 26, arrives at the Keller home having shunned her "guilty" father since his imprisonment. Throughout the play, Ann is often referred to as pretty, beautiful, and intelligent-looking and as "Annie". She had a relationship with Larry Keller before his disappearance, and has since moved on because she knows the truth of his fate. She hopes that the Kellers will consent to her marriage to Larry's brother, Chris, with whom she has corresponded by mail for two years. Ann soon finds out that the neighbors all believe that Joe is guilty, and eventually finds out the truth after a visit from her older brother George. Ann is the knowledge-bearer in the play: finally, unable to convince Kate that Larry is gone forever, Ann reveals a letter from Larry stating his intention to commit suicide having learned of his father’s implied guilt.
George Deever — George, 31, is Ann’s older brother: a successful New York lawyer and WWII veteran, and a childhood friend of Chris'. He initially believed in his father’s guilt, but upon visiting Steve in jail, realizes his innocence and becomes enraged at the Kellers for deceiving him. He returns to save his sister from her marriage to Chris, creating the catalyst that destroys the Keller family.
Jim Bayliss — Jim is a successful doctor, but is frustrated with the stifling domesticity of his life. He wants to become a medical researcher, but continues in his job as it pays the bills. He is a close friend to the Keller family and spends a lot of time in their backyard.
Sue Bayliss — Sue is Jim's wife: needling and dangerous but affectionate, she too is a friend of the Keller family, but is secretly resentful of what she sees as Chris's bad idealistic influence on Jim. Sue confronts Ann about her resentment of Chris in a particularly volatile scene, revealing to Ann that the neighbors all think Joe is guilty.
Frank Lubey — Frank, 33, was always one year ahead of the draft, so he never served in World War II, instead staying home to marry George's former sweetheart, Lydia. He draws up Larry's horoscope and tells Kate that Larry must still be alive, because the day he died was meant to be his "favorable day". This strengthens Kate's faith and makes it much harder for Ann to reveal the letter to her.
Lydia Lubey — Lydia, 27, was George's love interest before the war; after he went away, she married Frank and they quickly had three children. She is a model of peaceful domesticity and lends a much-needed cheerful air to several moments of the play.
Bert — Bert is a little boy who lives in the neighborhood; he is friends with the Bayliss' son Tommy and frequently visits the Kellers' yard to play "jail" with Joe. He only appears twice in the play. The first time he appears, his part seems relatively unimportant, but the second time he appears his character gets more important as he sparks a verbal attack from mother when mentioning "jail," which highlights Joe's secret.
Larry Keller — Larry has been MIA for some years at the start of the play. However he has a significant effect in the play through his mother's insistence that he is still alive and his brother's love for Larry's childhood sweetheart, Ann. Comparisons are also made in the story between Larry and Chris; in particular, their father describes Larry as the more sensible one with a "head for business". At the end of the play, Ann reveals a letter written by Larry saying that, out of shame for his father's actions, he intends to commit suicide.
Steve Deever — George and Ann's father. Steve is sent to prison for the shipping of faulty aircraft parts — a crime which not only he but also the exonerated Keller committed.