- Dr. Elwin Ransom – A professor of philology at a college of the University of Cambridge, hence gifted with languages. He befriends first many hrossa, then some sorns, and at last Oyarsa.
- Dr. Weston – A thick-set physicist, savage, arrogant and greedy, who considers himself ultra-civilized. He mocks "classics and history and such trash" in favor of the hard sciences and imperialism and, boasting to Ransom about his achievements in interplanetary travel, declares, "You cannot be so small-minded as to think that the rights of an individual or of a million individuals are of the slightest importance in comparison with this."
- Dick Devine – Later a politician, Weston's "power-hungry accomplice" possesses "that kind of humour which consists in a perpetual parody of the sentimental or idealistic clichés of one's elders." "He was quite ready to laugh at Weston's solemn scientific idealism. He didn't give a damn, he said, "for the future of the species or the meeting of two worlds." He instead is motivated solely by greed for wealth and seeks to exploit Malacandra for its gold.
- Hyoi – Ransom's first hross friend; they meet in Chapter 9, and Hyoi begins to teach him the Old Solar language and the practical philosophy of the hrossa. Hyoi is murdered by Weston.
- Hnohra – An older hross who teaches Ransom to speak Old Solar.
- Augray – A sorn who saves Ransom from near death on his freezing mountain-top, asks him many questions about Earth, and carries him to Meldilorn to meet Oyarsa.
- Kanakaberaka – A pfifltrigg who carves Ransom's portrait onto a stone at Meldilorn.
- Oyarsa is undying, wise, and compassionate. He is the greatest eldil to visit Malacandra and functions as its ruler. Oyarsa tells Ransom that he "sent for" Ransom to visit him from Thulcandra (thus establishing Ransom's special qualities in later books).