George is the patriarch of the Antrobus household and acts as an allegorical representation of the biblical Adam. Operating as a modern suburban father who invents foundational tools like the wheel and the alphabet, he places immense value on human culture, philosophy, and education. He functions as a leader during times of crisis but struggles with pride and an easily provoked temper.

Maggie is the pragmatic matriarch of the family, acting as the allegorical counterpart to Eve. She manages the domestic realities of her household, prioritizing the physical survival of her children above everything else. Her tough, practical demeanor contrasts sharply with her husband's focus on intellectual pursuits.

Henry is the Antrobus family's son, a boy who bears a persistent, bright red scar on his forehead. Known formerly by another name before a tragic family incident, he represents the biblical Cain and embodies humanity's aggressive instincts. He struggles to control his violent temper, creating constant stress for his parents.

Gladys is the Antrobus family's daughter, subjected to intense scrutiny regarding her modesty and posture. Her parents pressure her to maintain the image of a perfectly innocent child, though she quietly rebels against these restrictions to explore her own identity. She proves capable and helpful during moments of crisis.

Sabina is the Antrobus family's maid, a highly made-up woman who resents her domestic duties and frequently attempts to seduce George. The character regularly breaks the fourth wall, dropping her persona to reveal herself as Miss Somerset, an actress who actively dislikes the production she is starring in. She represents indulgence, vanity, and the desire for easy comfort.

Mr. Fitzpatrick is the stage manager for the theatrical production. He attempts to maintain order and keep the performance running smoothly, managing both uncooperative actors and technical emergencies. He acts as the voice of backstage authority.

The Refugees are a large group of historical and cultural figures—including Homer, Moses, a doctor, and the Muses—seeking shelter from the extreme cold. They represent the accumulation of human knowledge, art, and law.

Esmeralda is a fortune teller who issues blunt predictions about bad luck and impending disasters. She addresses the audience directly to share her insights on human nature, possessing a cynical certainty about the cyclical nature of destruction and survival.

The Animals represent the non-human creatures sharing the earth with humanity. They first appear as the Antrobus family's talking pets—a mammoth and a dinosaur—and later as delegates attending the Atlantic City convention, seeking survival alongside mankind.

The Human Conveeners are attendees at the Atlantic City convention. They act as a collective chorus of revelers who mock preparations for disaster, preferring to spend their time gambling at bingo and enjoying the boardwalk until danger is unavoidable.

The Hours Of The Night is a group composed of theater crew members, including a wardrobe mistress, an usher, and a maid. Drafted at the last minute to save the production, they represent the passing night hours by reciting the words of great philosophers.

Fred is the theater's usher captain. He acts as a stand-in for a sick actor, taking on the role of the philosopher Spinoza to represent nine o'clock.

Hester works as the wardrobe mistress for the theatrical company. She steps out of her backstage role to portray Plato, representing ten o'clock in the philosophical sequence.

Ivy is Miss Somerset's personal maid. She shares her theological insight into the production before stepping onto the stage to play Aristotle, representing eleven o'clock.

Mr. Tremayne is a former Shakespearean actor currently working as the lead actor's dresser. He takes the stage to recite the opening lines of the Bible, representing midnight.

The Telegraph Boy is a twelve-year-old messenger who navigates the freezing weather to bring news to Maggie. He seeks warmth and advice for his own young family as the ice age descends.