Dr. Elwin Ransom is a linguistics professor at Cambridge University on a year-long sabbatical. He is an intelligent, ordinary, and empathetic man whose scientific background fuels a genuine curiosity about the universe. Kidnapped and taken to Malacandra, his open-mindedness helps him understand the unfamiliar planet and its inhabitants.

Dr. Weston is a brilliant physicist who firmly believes in the supremacy of the human race and the necessity of interplanetary colonization. He is utterly driven by a cold, progress-at-all-costs scientific idealism. He treats the inhabitants of other planets as inferior beings to be conquered for the survival of humanity.

Devine is a former schoolmate of Ransom's who has mysteriously acquired substantial wealth since leaving Cambridge. Cynical and materialistic, he funds space travels purely for the opportunity to extract valuable resources like gold from other planets. He lacks moral convictions, seeking only personal financial gain.

Hyoi is a tall, seal-like creature belonging to the rational Malacandrian species known as hrossa. He possesses a distinct language, a deep philosophical acceptance of life, and an open, peaceful nature. His willingness to communicate helps bridge the gap between his people and humanity.

Oyarsa is the spiritual ruler of Malacandra and the greatest of the angelic eldila. Made of light rather than physical matter, he governs the planet's diverse species with wisdom and peace. He serves as the voice of higher divine powers and evaluates the intentions of visitors to his world.

Maleldil the Young is a divine, Christlike spiritual figure in the Malacandrian religion who created the world and continues to rule over it alongside The Old One. He ensures that the planet's inhabitants have everything they need to live in harmony.

The Old One is the supreme spiritual ruler of the universe. He resides in the heavens and commands the various oyarses of the solar system, overseeing the cosmic balance from afar.

Earth's former oyarsa who became evil, or bent, long ago. Cast out of the cosmic community and confined to Earth's atmosphere, he is responsible for corrupting humanity with fear, greed, and the instinct for violence.

Harry is a young man described as a little simple who works as a servant at The Rise. His distress and vulnerability make him the initial intended target of Weston and Devine's kidnapping plot.

She is Harry's mother, living in the English countryside. Her deep worry over her vulnerable son prompts Ransom to investigate the disturbing events at The Rise.

Augray is a member of the séroni (sorns), the tall, humanoid species of Malacandra. He lives in a tower in the highlands and possesses scientific knowledge, kindly assisting Ransom with survival gear for the thin atmosphere.

Whin is a hross from Hyoi's village who takes part in the dangerous expedition to slay the reptilian hnakra. He advises Ransom on the correct path to reach Meldilorn.

Hnohra is an older hross who teaches Ransom about the Malacandrian cosmos. He reveals that Earth is isolated from the rest of the planets and is known universally as Thulcandra.

Kanakaberaka is a member of the pfifltriggi, the hairless, long-snouted, and multi-fingered species of Malacandra. He is a skilled artisan who works with gold and explains his people's communal approach to resources.

Hrinha is a hross who operates the boat to the island of Meldilorn. His role demonstrates how his species' natural affinity for water serves the broader planetary community.

The narrator is a former student of Dr. Ransom who later contacts him to ask about an ancient Latin text regarding space travel. He eventually collaborates with Ransom to publish the story of Malacandra as a work of fiction to prepare humanity for future cosmic threats.