Jack is a former newspaper reporter who works as a political researcher for Governor Willie Stark, tasked with digging up damaging information on political opponents. Raised in the wealthy, aristocratic enclave of Burden's Landing, he is a cynical operative who previously abandoned a PhD in history. He struggles with a nihilistic worldview, occasionally falling into periods of deep apathy he calls the "Great Sleep" when he cannot make sense of the facts in front of him.

Willie, known as "the Boss," is the populist governor of the state who rose from a naive county treasurer to a ruthless political powerhouse. He relies heavily on political theater, blackmail, and bribery to maintain his grip on the government while championing public works projects for the working class, including a massive free hospital. His idealistic beginnings have gradually given way to a belief that all human actions are inherently corrupt and that the law is highly malleable.

Judge Irwin is an elderly, aristocratic resident of Burden's Landing and a stalwart figure of the traditional political establishment. He projects an image of unwavering integrity and steadfastly refuses to support Willie Stark's political machine. As the target of Jack's political opposition research, he insists that his conscience dictates his endorsements, remaining unintimidated by Willie's threats.

Adam is a highly skilled, successful surgeon and the son of former Governor Stanton. Raised in the wealthy enclave of Burden's Landing, he is a strict idealist who actively despises Willie Stark's corrupt methods. He approaches medicine with an obsessive need to fix broken things, maintaining a rigid moral code that isolates him from the messy realities of state politics.

Anne is a resident of Burden's Landing who spends her time reading and doing charity work following several broken engagements and her father's death. She possesses a deep-seated optimism, consistently expecting the best from the people around her. Despite her aristocratic background, she actively lobbies for state funding for the Children's Home, drawing her into the orbit of Willie Stark's administration.

MacMurfee is Willie Stark's primary political rival and a powerful player in state politics. He constantly maneuvers to undermine Willie's authority, utilizing political operatives to dig up scandals and threatening Willie's long-term ambitions for the US Senate.

Sadie is Willie Stark's fiercely intelligent, calculating secretary and political strategist. She initially entered Willie's orbit to monitor his first, doomed gubernatorial campaign, but her blunt honesty about the political machine helped forge him into a ruthless operator. She wields information aggressively and expects total loyalty from those around her.

Tiny Duffy is a career politician who serves as Willie Stark's lieutenant governor, despite Willie frequently insulting and humiliating him. Originally sent to trick Willie during his first campaign, Duffy represents the entrenched, self-enriching political establishment that Willie claims to oppose. He constantly advocates for granting lucrative state contracts to wealthy insiders.

Lucy is Willie Stark's wife, a former schoolteacher who finds herself increasingly alienated by the dark, corrupting reality of state politics. Though she poses for photographs to maintain the illusion of a happy political family, she physically separates from Willie out of moral disgust over his protection of corrupt officials.

Tom is Willie and Lucy's son, a confident and highly talented college football player. His father actively uses his athletic success to bolster his own populist image, while his mother worries about his erratic behavior. Growing up in the shadow of his father's massive political footprint leaves him reckless, entitled, and prone to trouble.

Sugar-Boy is Willie Stark's fiercely loyal driver and bodyguard. He is a quiet, highly skilled marksman who trails Willie constantly to ensure his physical safety in an increasingly hostile political environment.

Ellis Burden is Jack's presumed father, who abandoned his family years ago. He now lives in squalor above a restaurant, having renounced his past life in Burden's Landing. He spends his time caring for unfortunate individuals and refuses to answer Jack's questions about his former associates in the political sphere.

Governor Stanton is Adam and Anne's late father, a former governor who represents the old-guard aristocracy of Burden's Landing. His children revere him as a paragon of political nobility, though Jack's investigations into state contracts threaten to complicate this pristine legacy.

Cass Mastern is Jack Burden's great-uncle, a Civil War-era figure whose journals and letters formed the basis of Jack's abandoned PhD dissertation. A deeply religious man who struggled with personal sins and the morality of enslavement, his complex life completely paralyzed Jack's ability to write history.

Gummy Larson is a wealthy, strictly-business contractor and a major financial backer of MacMurfee's political machine. He represents the transactional nature of state politics, willing to sell his loyalty to the highest bidder for lucrative state construction projects.