Michel is a 25-year-old scholar from a middle-class French family. Raised by an atheist father and a strict Protestant mother, he initially dedicates himself entirely to studying the ancient history of the Roman Empire. Following a severe bout of tuberculosis during his honeymoon in North Africa, his personality undergoes a profound shift. He develops an intense focus on living in the present, pursuing physical health, and experiencing sensual pleasures, causing him to increasingly reject the societal conventions of his past.

Marceline is a beautiful, intelligent Catholic woman who comes from a modest background. She represents conventional domesticity and societal expectations. As a devoted wife, she patiently acts as Michel's caregiver during his debilitating illness in Biskra, going to great lengths to bring him comfort, including inviting local children to entertain him. Her traditional values and physical fragility place her at odds with her husband's newfound philosophy of uninhibited self-indulgence.

Charles is the 17-year-old son of Bocage, the manager of Michel's property in Normandy. He trains at a model farm and possesses a modern, pragmatic approach to agricultural management. Handsome and physically capable, he eagerly embraces hard labor and displays a confident mastery over nature, impressing Michel with his youthful vitality and his willingness to challenge the traditional methods of his father.

Ménalque is a notorious hedonist who works for the Ministry of the Colonies. Known for his scandalous reputation and piratical appearance, he openly flouts social conventions and prioritizes personal pleasure above all else. He frequently travels abroad and views material possessions with a detached irony, offering philosophical encouragement to Michel as he seeks to abandon traditional morality.

Bachir is an Arab boy living in Biskra, Algeria. He possesses robust health and a careless vitality that deeply affects Michel. His nonchalant reaction to accidentally cutting himself with a knife serves as a catalyst for Michel's determination to overcome his tuberculosis.

Moktir is a local boy in Biskra who initially presents as well-behaved. He catches Michel's distinct interest when he secretly pockets a pair of Marceline's scissors, an act of petty theft that Michel observes but chooses not to report.

Bocage is the traditional estate manager at La Morinière. He oversees the property's daily operations and staff but operates under older, less efficient methods. He remains oblivious to both his younger son's illegal poaching and Michel's growing dissatisfaction with his management.

Alcide is Bocage's younger son. Rather than working legitimately on the farm, he secretly sets illegal traps on the property and sells the poached game for personal profit, amusing Michel in the process.

The unnamed narrator is a childhood friend of Michel. He travels to a remote village in Tunisia with two other friends, Denis and Daniel, in response to Michel's plea for help. He acts as the audience for Michel's confession and transmits the story in hopes of securing his friend a purposeful position.

Lassif is a 12-year-old goatherd whom Michel and Marceline meet while walking through the North African orchards. His idle, pastoral lifestyle appeals to Michel's growing appreciation for sensual simplicity and nature.

Lachmi is an orchard worker and brother to Lassif. He spends his days in the pastoral environment near Biskra, contributing to the serene atmosphere that captures Michel's attention.

Ashour is a 14-year-old Black boy whom Michel befriends during his solitary walks in Biskra. His presence provides Michel a refreshing change from Bachir as he explores the local community.

Bute is a farmhand on Michel's estate who shares scandalous local gossip. He supplies Michel with wire to build illegal game traps before causing a drunken altercation when the funds dry up.

Pierre is a laborer on the estate. He works hard but struggles with frequent drunkenness, leading to his dismissal by Bocage—a decision that frustrates Michel, who admires the man's uninhibited vices.

Michel's father is a wealthy atheist and scholar. He instills thrifty habits in his son and expresses a dying wish to see Michel settled in marriage, prompting Michel's engagement to Marceline.

Michel's mother is a Huguenot whose strict religious devotion and early death deeply impact Michel. He channels her austere influence into a fanatical dedication to his historical studies during his youth.

Heurtevent is a local wood merchant near the La Morinière estate. He is the subject of dark local rumors and actively buys illegally poached game from Alcide.

Denis is one of Michel's childhood friends who honors a long-standing pledge of mutual aid, traveling across the Mediterranean to find Michel after receiving his urgent message.

Daniel is another of Michel's old school friends who journeys to North Africa to answer Michel's call for help, demonstrating his commitment to their youthful pact.

Monsieur D. R. is the President of the Council. He is the recipient of the narrator's letter detailing Michel's confession, asked to use his political influence to find Michel a purposeful job.