The unnamed narrator is an algebra teacher living in Harlem who has built a stable, upwardly mobile life for his family. He relies on order and practicality to escape the poverty and systemic racism of his childhood. Despite his disciplined exterior, he carries deep emotional wounds and struggles to understand his brother's artistic, unstructured lifestyle.

Sonny is a passionate and idealistic jazz musician who carries the heavy psychological weight of his environment. Unlike his older brother, he prioritizes creative expression over conventional stability. He uses the piano as an outlet for his emotional pain but also battles a severe heroin addiction that complicates his freedom and family ties.

Daddy is the stern, alcohol-dependent father of the narrator and Sonny. He carries a lifelong trauma stemming from a horrific incident of racist violence in his youth. This hidden pain makes him outwardly tough and overprotective, especially toward his younger son.

Mama is the resilient matriarch of the family who understands the harsh realities of growing up Black in America. She acts as the emotional anchor for her husband and sons, carrying the burden of family secrets while trying to prepare her children for an unforgiving world.

Isabel is the narrator's practical and welcoming wife. She helps maintain the stable, respectable household that her husband deeply values. Her extended family temporarily takes Sonny in during his teenage years, though they struggle to tolerate his constant piano practice.

Creole is a seasoned musician who plays alongside Sonny. He acts as a guiding force on the bandstand, helping to create a supportive environment where Sonny can freely express his trauma and talent through his instrument.

An unnamed acquaintance from Harlem who grew up around the brothers. He approaches the narrator out of a sense of guilt, feeling partially responsible for Sonny's path because he once described the sensation of getting high to him.

Young Isabel is the daughter of the narrator and his wife, named after her mother. She contracts a sudden illness that shatters the narrator's carefully constructed world and alters his perspective on suffering.