The 51-year-old Irish Catholic captain of HMS Terror assumes primary leadership of the Franklin Expedition after Sir John Franklin's demise. An experienced and pragmatic seaman, he feels undervalued by his English peers and harbors a dependency on the ships' dwindling alcohol supply. He struggles to maintain order among a freezing, scurvy-ridden crew while an unknown predator stalks them across the ice.

The original commander of the expedition, Franklin is a confident but stubbornly optimistic officer who believes British naval technology can conquer the Arctic. He leads the HMS Erebus and HMS Terror into the Northwest Passage, relying heavily on his religious faith. His decisions to push forward despite worsening ice conditions strand the ships and seal the expedition's fate.

An Inuit woman taken aboard the expedition ships after a fatal misunderstanding results in her father's death. The crew nicknames her "Lady Silence" because she lacks a tongue and cannot speak. She possesses a deep understanding of the Arctic environment, making her an object of intense suspicion among the superstitious sailors.

A massive, terrifying predator stalking the crews of the HMS Erebus and HMS Terror across the ice. It resembles an impossibly large polar bear but exhibits intelligence and persistence far beyond a natural animal. It breaks through the reinforced hulls of the ships and picks off the crew one by one in the freezing darkness.

A caulker's mate aboard HMS Terror who operates near the bottom of the expedition's social hierarchy. He is a calculating opportunist who exploits the gaps in naval authority. As conditions worsen and morale drops, he uses rumors, fear, and violence to manipulate his fellow sailors.

An assistant surgeon and naturalist serving aboard the expedition. Young and scientifically minded, he joined the voyage hoping to study polar wildlife. His medical training provides a clinical perspective on the crew's deteriorating health, and he maintains his sense of empathy and duty even as discipline breaks down around him.

A confident young lieutenant aboard HMS Terror. He develops a quiet infatuation with Lady Silence and takes it upon himself to ensure she is sheltered from the harsh conditions. His adherence to naval protocol puts him at odds with the more rebellious members of the crew.

The executive officer aboard HMS Erebus who assumes command of the ship after Franklin's demise. He is an affable and optimistic officer who tries to maintain morale through traditional naval camaraderie and organized events, though he physically deteriorates as the isolation continues.

The pragmatic Ice Master aboard HMS Terror. He possesses extensive experience navigating treacherous polar waters and often provides blunt, realistic assessments of the expedition's dire circumstances, refusing to give in to the crew's growing superstitions.

Sir John Franklin's dedicated wife in England. She uses her influence to support her husband's career and remains a driving force behind organizing rescue efforts from afar when the expedition fails to return.

Sir John Franklin's niece. She rejected Francis Crozier's marriage proposal before the expedition, an event that still haunts the captain during his isolation in the Arctic.

A physically imposing but easily frightened sailor aboard HMS Terror. He falls under the influence of Cornelius Hickey and assists him in his schemes while struggling with his own superstitions and fears of the dead.

A seasoned sailor aboard Terror who maintains a secret, affectionate relationship with John Bridgens. He keeps a careful eye on the crew's morale and documents his experiences and the expedition's decline in a personal journal.

An older, educated steward aboard Erebus who previously sailed with Charles Darwin. He observes the deteriorating situation with philosophical detachment and provides a grounding presence for Peglar.

A second mate who leads scouting parties across the ice. He executes his orders dutifully despite the increasingly perilous conditions and frequent attacks by the creature.

A lieutenant who assists in search parties and tries to maintain order, though his judgment is sometimes clouded by the crew's growing fear, prejudice, and the manipulative lies of others.

A capable lieutenant tasked with leading the most critical scouting mission early in the expedition's entrapment. His party is the first to directly encounter the deadly realities of the King William Land environment.