As the end of the male line of McCaslins, Isaac McCaslin, in the eyes of the family, has a more legitimate claim to the plantation than the Edmonds heirs, who descend from the female line. An introspective man, Isaac believes the land, indeed the whole South, is cursed by the racism and dominance that have forged these properties. In fact, he believes ownership of land is immoral and illegitimate at its core. In renouncing his claim to the McCaslin lands and fortune, he gives full control to his cousin Cass Edmonds and gives up ownership of most material possessions. At the end of his life, widowed and childless, he has passed his house in Jefferson to his wife's sister and children and spends whatever time he can in the remaining wilderness areas near town.
As the son of Buck and Buddy's sister, Cass becomes a custodian of sorts for the McCaslin plantation and for Isaac McCaslin himself after the deaths of Cass's uncles Buck and Buddy. Because Buck is in his 70s when he fathers Isaac, Cass becomes more like a father figure and brother to his young cousin. He takes Isaac on hunting expeditions starting when the boy is 11 and Cass about 27. When the adult Isaac expresses his desire to renounce his inheritance, Cass tries to dissuade him, for Cass holds firmly with the family, and Southern, tradition that property should be passed down through the male line. Cass is less concerned with the considerable material gain Isaac's decision offers him than he is with maintaining tradition.
Because Carothers McCaslin didn't offer his name to any of his slaves, not even the ones he fathered, Lucas Beauchamp and his siblings take their surname from their mother's former owner. However, Lucas knows he is descended from Carothers McCaslin and uses this ancestry as a form of leverage over the white men who would otherwise seek to dominate his life. A good father and husband, he keeps his house, on the Edmonds/McCaslin plantation, in good condition. He reserves his strongest resistance for Cass Edmonds's son Zack. When Zack tries to steal Lucas's wife, Lucas and Zack enter into a violent confrontation in which Lucas almost kills Zack. In later years Lucas expresses quiet rebellion by distilling whiskey on the plantation and nearly drives his wife to divorce him when he becomes obsessed with finding buried treasure.
Rider is the only major character in Go Down, Moses who has no clear family connection to the McCaslins. His physical strength is legendary but can't save him after his wife dies of unspecified causes. Having given up drinking and carousing after his marriage, Rider reverts to former ways after her funeral, acts that ultimately lead to his lynching.
Sam lives on the McCaslin plantation and works as a carpenter. He is the son of Ikkemotubbe, the Chickasaw chief who sold Carothers McCaslin the land for the plantation. Ikkemotubbe also sold McCaslin Sam's mother, a slave woman characterized as "quadroon," meaning she has one black grandparent. This distinction matters for her and for Sam, who must live by the rules governing black society. Sam's special interest in young Isaac McCaslin likely shapes Isaac's rejection of property ownership.
Born Lucius Quintus Carothers McCaslin, he is a major influence on the dynamics and action of most of the stories. McCaslin family history holds Carothers bought his plantation near Jefferson from a Chickasaw chief, Ikkemotubbe. McCaslin has three children by his white wife: Buck, Buddy, and an unnamed daughter. Carothers also has two children by slave women on the plantation: Tomasina (Tomey) from his union with Eunice, and Terrel, called Tomey's Turl, from his incestuous union with Tomey, his daughter.
Born Zachary to Cass Edmonds and his wife, Alice, Zack takes control of the McCaslin plantation without any of the hesitation his father showed when Isaac handed the land over to him. After Zack's wife dies giving birth to their son, Roth, Molly Beauchamp comes to the main house to help care for the infant and stays for six months. The text strongly implies an affair between them, leading Lucas Beauchamp to try to kill Zack. The two reach an uneasy peace partly on the basis of the mutual knowledge they are cousins.
Roth Edmonds is the last man to control the Carothers plantation. In Go Down, Moses, he has no wife and no legitimate children to inherit the property. As a landowner, Roth wields considerable power over his tenants. He is characterized as strict but not necessarily menacing. He shares his grandfather Cass's propensity for hunting and his great-great-grandfather Carothers's propensity for illicit affairs. Roth has a relationship, and infant son, with a mixed-race woman, who is James Beauchamp's granddaughter and consequently Roth's third cousin.