Ahmad is a devout, highly educated Arab Muslim accustomed to the comforts, warm climate, and strict etiquette of his home city. Exiled on a diplomatic mission after a social transgression, he finds himself thrust into the harsh, unfamiliar environment of Northern Europe. He acts as a reluctant observer and anthropologist, meticulously documenting the strange customs, hygiene, and combat practices of the Norsemen. When a soothsayer decrees that a thirteenth warrior must join a dangerous rescue mission, Ahmad is forced into the war band despite his protests.

Buliwyf is a towering, tactically brilliant Norse warrior who physically and spiritually embodies his people's heroic ideals. He carries a giant sword named Runding and commands the absolute loyalty of his men through his stoic bravery. When a messenger arrives begging for help against an ancient terror, Buliwyf readily accepts the perilous mission to defend a distant kingdom. He shows a surprising, quiet curiosity about Ahmad's ability to read and write.

Herger is a seasoned Norse warrior and Buliwyf's loyal subordinate. Because he shares a common language with Ahmad, he becomes the Arab ambassador's primary guide, translator, and cultural liaison. Herger is fierce in battle and deeply committed to his people's martial code. He initially finds Ahmad's religious devotion and constant complaints amusing, but he serves as a brutal yet effective teacher for the foreigner.

Wiglif is Rothgar’s ambitious, ruthless son and the heir apparent to the kingdom. He secured his position by eliminating his rival brothers, demonstrating a cunning and self-serving nature. Rather than focusing on defending his father's people from the wendol, he views Buliwyf's arrival with deep suspicion and actively schemes against the rescuing warriors to protect his own political dominance.

The Mother of the Wendol is the central figure and apparent deity of the cannibalistic tribe plaguing Rothgar's lands. Represented by crude stone idols covered in blood, she resides in a secure, snake-filled cavern where she commands the absolute, violent devotion of her followers.

Rothgar is the aging king of a northern territory currently terrorized by a cannibalistic threat known as the wendol. Having built the lavish Hurot Hall on a mountaintop, he now finds himself unable to protect his people from nocturnal massacres. His physical decline and inability to secure his own realm stand as a cautionary example to the younger Norse warriors about the loss of martial strength in old age.

The Unnamed Editor acts as an academic narrator framing the entire novel. He curates, annotates, and provides historical context for Ahmad's 10th-century account. Through frequent footnotes and appendices, he interrupts the story to analyze the plausibility of the events, critique Ahmad's cultural biases, and offer scientific or anthropological explanations for the bizarre phenomena the Arabs and Norsemen encounter.

Wulfgar is a young noble and one of the last surviving sons of King Rothgar. He serves as the brave messenger who travels across the dangerous sea to find Buliwyf and formally request his military aid against the forces attacking his father's kingdom.

Wyglif is the aging Norse leader whom Ahmad first encounters on his travels. His illness and subsequent death create a power vacuum, prompting the election of Buliwyf as the new leader. Wyglif is given a massive, violent, and days-long funeral rite that deeply shocks the observing Ahmad.

Thorkel is an ambitious Norseman who attempts to usurp power following the death of the old chief. He falsely accuses Ahmad of conspiring with Buliwyf, hoping to turn the community against the newly elected leader and claim the top position for himself.

The "angel of death" is a title given to an elderly woman in Norse society who performs important, often bloody, religious rituals. She acts as an oracle for the warriors, casting bones to divine the future. It is her decree that demands Buliwyf recruit a thirteenth warrior for his rescue mission.

Ragnar is a warrior in Rothgar's kingdom and a close friend to the king's ambitious son, Wiglif. He actively participates in Wiglif's political machinations against the visiting Norsemen until he is directly provoked into a violent duel.

Ecthgow serves as Buliwyf's trusted lieutenant in the war band. He is a steadfast warrior who helps manage the men and maintains morale by sharing grim stories of sea monsters during their dark journey across the ocean.

Tengol is an old person with dwarfism who serves as a respected soothsayer and specialized weapon-maker for the Norsemen. Living apart from the main community, Tengol provides Buliwyf with crucial tactical advice and the physical tools necessary to launch an honorable counterattack against the wendol.