An American serving as an officer and ambulance driver in the Italian army during World War I. He presents a detached and somewhat passive demeanor, coping with the grim reality of the conflict through heavy drinking and visiting brothels with his fellow soldiers. He questions the abstract rhetoric of military glory and seeks a sense of meaning outside the rigid military structure.

A British Voluntary Aid Detachment nurse working in Italy. She carries the recent trauma of losing her fiancé in combat. Despite her grief, she actively chooses to pursue a relationship with Frederic. She views their bond as a way to create meaning and stability in the chaotic wartime environment.

A skilled surgeon in the Italian army and Frederic's roommate. He uses heavy drinking and constant joking to stave off the psychological toll of operating on endlessly broken bodies. He is highly affectionate toward Frederic but grows increasingly bitter as the war drags on.

A young Catholic chaplain serving with the Italian army. He hates the war and wishes to return to the cold, clear mountains of his hometown. He maintains his faith and dignity despite the constant baiting from other officers, offering a quiet spiritual alternative to their cynicism.

A Scottish nurse working alongside Catherine at the hospital. She is highly protective of Catherine and deeply concerned about wartime propriety. She worries about the consequences of Catherine and Frederic's rapid, secretive romance.

A practical American nurse who attends to Frederic in Milan. She maintains a relaxed attitude about hospital rules and covers for his secret drinking.

The superintendent of the American hospital in Milan. She is a strict disciplinarian focused on maintaining order in her facility. She views Frederic's behavior with immediate suspicion and rigidly enforces hospital rules.

A confident Italian major and surgeon. Unlike the cautious hospital doctors who want to wait six months, he is cheerful, decisive, and willing to operate on Frederic immediately.

Frederic's superior officer at the front. He is a pragmatic military man who watches the toll the conflict takes on the men, noting how the summer battles have exhausted the medical staff.

An ambulance driver under Frederic's command. He strongly opposes the war, arguing that defeat is better than the endless slaughter of combat. He openly speaks out against the ruling class that prolongs the conflict.

An ambulance driver working in Frederic's unit. He acts as a nurturing figure among the men by ensuring they eat hot meals. He also attempts to protect vulnerable civilians encountered on the road.

An Italian ambulance driver working under Frederic. He holds socialist political views and remains fiercely loyal to his commanding officer during dangerous military operations.

An ambulance driver under Frederic. He maintains a cynical attitude and prioritizes his own survival. He is willing to take extreme actions rather than risk death or capture during combat operations.

A 94-year-old nobleman whom Frederic encounters while staying at a hotel. He maintains a sharp mind, playing billiards and drinking champagne. He offers Frederic a blunt, wise perspective on the war.

An American studying singing in Italy. He acts as a helpful, unquestioning contact for Frederic when he returns to Milan in need of civilian clothes.

An Italian-American from San Francisco serving in the Italian army. He is a decorated soldier who openly brags about his medals and ambitions for promotion. He stands in direct contrast to Frederic's lack of military zeal.