Ferdinand is a medical student in Paris who impulsively enlists in the French army at the outbreak of World War I. His traumatic experiences on the front lines quickly strip away his youthful optimism, leaving him cynical and focused purely on physical survival. He travels extensively across continents, taking on odd jobs in colonial Africa, industrial Detroit, and the Parisian suburbs, constantly seeking geographical escape from his own unexamined trauma.

Robinson is a reservist soldier who shares Bardamu's deep fear and resentment of the senseless violence driving World War I. He functions as a fellow traveler on Bardamu's journey, consistently appearing a step ahead in their shared attempts to avoid societal obligations. He pursues his own survival with absolute pragmatism, willing to discard conventional morality entirely if it benefits him financially.

Grandma Henrouille is an elderly woman confined to a small shack by her son and daughter-in-law, who hope to have her institutionalized to seize her pension. She harbors a fiery resentment toward her family and fiercely resists their attempts to lock her away in an asylum. When given the opportunity, she demonstrates a surprising entrepreneurial drive and a renewed desire to live independently.

Madelon is the daughter of a church candle seller who becomes engaged to Robinson in Toulouse. Unlike the men in her life, she takes declarations of love seriously and insists on actual emotional commitment. Her intense passion and demand for loyalty stand in stark opposition to the cynical detachment of her romantic partners.

Lola is an American woman who travels to France to support the war effort with intense patriotic enthusiasm. She organizes a group of cooks to make fritters for soldiers and begins a romantic relationship with Bardamu. Her idealized view of the war clashes directly with Bardamu's traumatized outlook.

Molly is an American sex worker who takes a genuine, unselfish interest in Bardamu's wellbeing while he works at the Ford Motor Company. She offers him financial support and unconditional affection, encouraging him to settle down and find a better job.

Monsieur Henrouille is a resident of the poor Parisian suburb of Rancy who obsessively guards the home he and his wife saved for decades to purchase. He resents the financial burden of his elderly mother and seeks unscrupulous ways to remove her from his property.

Madame Henrouille actively supports her husband's efforts to institutionalize Grandma Henrouille so they can collect her pension without the burden of care. She prioritizes the material wealth of her household over family loyalty.

Bébert is a young, impoverished boy living with his aunt in the Parisian suburbs. He maintains a pure, affectionate smile despite his difficult living conditions and recurring illnesses.

Bébert's aunt cares for her young nephew in the poor Parisian suburb of Rancy. She relies heavily on Bardamu's medical advice to treat Bébert's illnesses and worries constantly about the boy's habits and health.

Serge Parapine is a medical professional and scientist who grows disillusioned with his field and frequently complains about his lab assistant. He later loses his prestigious position due to inappropriate behavior and takes a job studying the effects of cinema on children.

Dr. Baryton is a psychiatrist who becomes obsessively fascinated with the English language and British culture. His intense focus on learning English from Bardamu eventually eclipses his interest in running his medical facility.

Arthur is Bardamu's friend in Paris before the outbreak of World War I. He watches the military parade alongside Bardamu but does not succumb to the same sudden burst of enthusiasm to enlist.

Musyne is a violinist and dancer who enters a brief relationship with Bardamu. She ultimately leaves him for a wealthy Argentinian war profiteer, prioritizing financial security over their connection.

Professor Bestombes is an enthusiastically patriotic doctor who uses electroshock therapy on traumatized soldiers. He views the war primarily as a fascinating opportunity to experiment on the human nervous system.

Protiste is a local priest who involves himself in the affairs of the Henrouille family. He acts as a middleman, proposing a scheme to relocate members of the community to Toulouse to avoid local scandal.

Sophie is a Slovakian nurse whom Bardamu dates while working at the asylum. She accompanies Bardamu, Robinson, and Madelon on a tense social outing to a local carnival.

Gustave is a local traffic cop who prefers eating at the asylum to avoid political arguments at the bar. He frequently plays cards with Bardamu and relies on the doctor to correct his poor vision.

Sergeant Alcide is a solemn French soldier running an illegal trading operation in the colonies. He saves his illicit earnings entirely to support his orphaned niece back in France, a motivation that briefly embarrasses Bardamu.

Lieutenant Grappa runs a gray-market business buying and selling goods in the colonial outpost. He routinely orders the physical abuse of local residents to administer his personal vision of justice.

Tania is a Polish dancer who initiates a relationship with Bardamu while she waits to return to her true love in Berlin. She uses the relationship primarily as a distraction from her longing.

The Director manages the colonial operation in Bambola-Fort-Gono. He praises life in the colony while hiding the harsh realities of the interior, warning Bardamu about the unreliable man he is replacing.

Voireuse is a former coworker of Bardamu who joins him in searching for pity and money from former employers and the grieving families of deceased soldiers.