The Kid is a pale, thin 14-year-old boy who flees his home in Tennessee to escape an abusive environment. Though he is illiterate, he possesses a natural instinct for violence that helps him survive on the road. He travels westward, taking menial jobs and getting into street fights before eventually joining organized mercenary groups. Despite his brutal surroundings, he occasionally shows brief flashes of compassion toward wounded companions.

Judge Holden is an immense, pale, completely hairless man who commands attention with his extreme physical size and vast intellect. He speaks multiple languages and meticulously documents the natural world in his notebook. He also delivers complex lectures on geology and philosophy. Although technically second in command to Glanton, he exerts tremendous ideological influence over the mercenary gang. He views existence as an endless war and seeks to dominate everything he encounters.

John Joel Glanton is a ruthless mercenary leader hired by the governor of Chihuahua to hunt Apache warriors. He commands a heavily armed gang of scalp hunters, prioritizing bloodshed and financial gain over human life. He uses his government contract as a convenient excuse to indulge his desire for continuous violence. Over time, he increasingly relies on Judge Holden's destructive guidance.

Louis Toadvine is a violent drifter lacking ears and bearing branded letters on his forehead. He meets The Kid during a tavern brawl, establishing a brutal but reliable companionship. He later negotiates for himself and his fellow prisoners to join Glanton's gang, securing their freedom in exchange for mercenary work.

Captain White is an American military officer who refuses to acknowledge the peace treaty between the United States and Mexico. He leads a rogue, unauthorized military expedition across the border, driven by intense racism and a desire for conquest. He actively recruits drifters into his ranks before leading his men south.

Ben Tobin is a former seminarian who rides with Glanton's mercenary gang. He frequently questions Judge Holden's blasphemous lectures and serves as a rare voice of ideological dissent. He acts as a wary mentor to The Kid, repeatedly warning him about the judge's strange powers.

Sproule is a wounded soldier in Captain White's company who originally traveled south to recover from consumption. He suffers a severe arm injury during a Comanche ambush and relies on The Kid for survival while wandering the desert.

Black Jackson is a mercenary riding with Glanton's scalp-hunting gang. He endures constant racial hostility from fellow gang members, which eventually provokes him to commit a lethal act of violence.

White Jackson is a racist mercenary in Glanton's horde. He aggressively attempts to enforce racial segregation around the campfires, leading to a deadly confrontation with another gang member.

Bathcat is a Welsh fugitive and member of Glanton's gang who boasts about hunting indigenous populations in Tasmania. He wears a necklace made of human ears and frequently gambles with the other mercenaries.

Grannyrat Chambers is a Kentucky veteran who previously fought in the Mexican-American War. He shares a jail cell with The Kid and Toadvine in Chihuahua City before joining the mercenary gang to secure his freedom.

Cloyce Bell is a recruit who joins Glanton's gang in Tucson, bringing his dependent brother along. He keeps his brother locked in a cage and exhibits him to crowds for money.

Cloyce's Brother is a mentally disabled man who is kept caged and exhibited by his sibling. Judge Holden takes a strange, intense interest in him, viewing him as a pure expression of uninhibited humanity.

Reverend Green is a traveling preacher delivering sermons in Texas. His religious revival is violently interrupted when Judge Holden falsely accuses him of heinous crimes, inciting the crowd against him.

The Hermit is a former slave trader living in isolation on the prairie. He offers The Kid temporary shelter from a storm while displaying a dried human heart as a trophy of his extreme racial hatred.

The Mennonite is an old man who encounters Captain White's soldiers in a tavern. He solemnly warns the men that their unauthorized military expedition into Mexico is doomed to fail.

Lincoln is a doctor running a ferry crossing on the Colorado River. He hires Glanton's gang to protect his operation from local threats, a decision that quickly results in his loss of control over the crossing.

Gomez is an Apache leader whose warriors defend their territory against encroaching settlers. The governor of Chihuahua places a massive bounty on his head, making him the primary target of Glanton's gang.