Tarwater is a fourteen-year-old boy raised in the Tennessee backcountry by his religiously fanatical great-uncle. Having lived a completely isolated life away from modern society, he is fiercely independent and deeply conflicted about the spiritual path demanded of him. He maintains a stubborn backwoods arrogance, actively resisting the secular re-education efforts of his city-dwelling uncle.

Rayber is a secular, rational city schoolteacher who harbors deep psychological scars from a childhood kidnapping by his uncle Mason. To ward off the threat of inherited mental illness and irrationality, he adopts a cold asceticism that suppresses strong emotions. He is determined to undo the religious indoctrination of his nephew and provide the boy with a strictly logical upbringing.

Mason is an eighty-four-year-old self-proclaimed Christian prophet living in the rural seclusion of Powderhead. Believing he acts on direct orders from God, he utilizes extreme measures to groom an heir to his prophetic mantle. His apocalyptic teachings and heavy expectations cast a long shadow over his surviving relatives.

The Friend is an invisible inner voice that emerges in Tarwater's mind following his great-uncle's death. It speaks from a highly skeptical perspective, mocking the old man's biblical ravings and urging Tarwater to reject his supposed spiritual duties. The voice acts as a persuasive companion who preys on the boy's insecurities and deep desire for independence.

Bishop is Rayber's intellectually disabled, mute son. He is entirely innocent and unaware of the fierce ideological battle raging between his father and cousin. His very existence serves as the central catalyst for the ideological conflicts plaguing the family.

Bernice is a social worker who briefly aligns with Rayber to rescue his nephew from Mason's influence. She marries Rayber but struggles with the emotional demands of their life together. Unwilling to raise a disabled child, she eventually abandons her family entirely.

Buford Munson is an African American neighbor living in the rural vicinity of Powderhead. He serves as a quiet, observant presence in the backcountry, stepping in to perform basic neighborly duties when the younger Tarwater fails to fulfill his immediate obligations.

Meeks is a practical traveling salesman who encounters Tarwater hitchhiking away from Powderhead. He provides the sheltered boy with a ride toward the city and assists him in using a telephone directory to locate his uncle.