- Mark Gainsby Studdock – Protagonist; sociologist, and ambitious to the point of obsession with reaching the "inner circle" of his social environment.
- Jane Tudor Studdock – Protagonist; Mark's wife. Jane is supposedly writing a Ph.D. thesis on John Donne, but since her marriage she has become effectively a housewife. In the course of the book she discovers herself to be a clairvoyant.
- vagabond tinker – mistaken by the N.I.C.E. for Merlinus Ambrosius when the latter steals his clothes and horse at his camp in Bragdon Wood.
N.I.C.E.
The National Institute of Coordinated Experiments (N.I.C.E.) is a scientific and social planning agency, furtively pursuing its program of the exploitation of nature and the annihilation of humanity. The Institute is secretly inspired and directed by fallen eldila, whom they refer to as "Macrobes", superior beings. Their takeover of Edgestow and its surrounding area shows the manner in which they use human pride and greed to get what they want. After the N.I.C.E. would achieve its ends, the earth would only belong to the "Macrobes".
- François Alcasan – "The Head", a French scientist executed for murder early in the book. His head is recovered by the N.I.C.E. and appears to be kept alive by the technology of man while actually having become a communication mechanism for the Macrobes.
- John Wither – Long-winded bureaucrat, Deputy Director of the N.I.C.E. He is the true leader of the N.I.C.E. and a servant of the Macrobes. Long association with them has "withered" his mind, and his speech and thinking are characterized by vagueness and jargon. He hardly ever sleeps, but instead maintains a continual dreamy wakefulness that perhaps affords him the ability to maintain a shadowy, supernatural presence throughout the Institute.
- Professor Augustus Frost – A psychologist and assistant to Wither, he is the only other N.I.C.E member who knows the true nature of the Head and of the Macrobes. He views emotions and values as mere chemical phenomena to be ignored as distractions from scientific inquiry. He is coldhearted and unemotional and he has an exact, precise manner of speech and thinking.
- Miss/Major Hardcastle (a.k.a. "The Fairy")– The sadistic head of the N.I.C.E. Institutional Police and its female auxiliary, the "Waips". Torture is her favorite interrogation method, and she takes special, sexual pleasure in abusing female prisoners.
- Dr. Filostrato – An obese Italian eunuch physiologist who has seemingly preserved Alcasan's head. He believes the Head to be truly Alcasan. His ultimate goal is to free humanity from the constraints of organic life.
- Lord Feverstone (Dick Devine) – The politician, recently ennobled businessman, and nominal academic who lures Mark into the N.I.C.E. Feverstone was one of the two men who kidnapped Ransom in Out of the Silent Planet , and the person responsible for getting Mark Studdock his fellowship at Bracton. A classic sociopath, he is motivated in all circumstances by the perceived benefit to himself. Although he is aware of the Macrobes, having encountered their benign counterparts on Mars, he has no interest in them.
- Reverend Straik – the "Mad Parson". He believes that any sort of power is a manifestation of God's will. Straik is ready to obliterate that "organisation of ordered Sin called Society". When Mark objects that he must not want to preserve Society because he believes in an afterlife, Straik objects that Jesus's real teaching was justice here and now. Emphasis on an afterlife has, he thinks, emasculated and sidetracked the real meaning of Jesus's teaching. This belief, along with other beliefs, makes him a suitable candidate for introduction to the Macrobes. Straik was "a good man once", but became deranged bythe death of his daughter.
- Horace Jules – A Cockney novelist, tabloid reporter, and pseudo-scientific journalist who has been appointed Director of the N.I.C.E. He studied science at the University of London, but clearly never advanced beyond an elementary level. He fondly imagines himself to be the actual leader of the N.I.C.E., but ashe is not aware of its true nature he is easily manipulated by Wither and Frost. He has a strong anti-clerical bias and objects to Wither appointing "parsons" (such as Straik) to the Institute. He is in part a caricature of H. G. Wells, whose book The Shape of Things to Come presented the systematic persecution of Christianity (and all other religions) by a future world government as a positive activity.
- William (Bill) Hingest – A distinguished chemist who is recruited by the N.I.C.E. but soon decides to resign, since he was expecting N.I.C.E. to be about science, but found some kind of political conspiracy instead; he makes no secret of his disdain for the Institute. Hence, he is murdered by N.I.C.E. agents.
St. Anne's
- Dr. Elwin Ransom (also known as "the Pendragon" and "the Director")– A former Cambridge don who heads the community at St. Anne's. He alone communicates with the benevolent eldila , whom he met during his earlier voyages to Malacandra and Perelandra (Mars and Venus). He has changed his surname to Fisher-King and has a wound in his foot, received on Venus, that will not heal till he returns there. His heavenly experiences have made him a kingly figure among his small band of followers, and he attributes his following to a divine Power, presumably Maleldil (Jesus Christ).
- Grace Ironwood – The seemingly stern but kind psychologist and doctor who helps Jane interpret her dreams. Her name is probably inspired by the Járnviðr ("Iron-Wood") of Norse mythology, its bleak connotations ameliorated by the Christian name "Grace".
- Dr. Cecil Dimble – Another academic, an old friend of Ransom, and close adviser on matters of Arthurian scholarship and pre-Norman Britain. He is fond of Jane Studdock, who was once his student, and feels guilty that he dislikes her husband Mark.
- Margaret "Mother" Dimble – The wife of Cecil Dimble. The Dimbles have no children, much to their sadness, but have compensated by their kindness to students. She is very maternal, and shows fondness towards Cecil's male and female students alike.
- Ivy Maggs – Formerly a part-time maid for Jane Studdock; now driven out of the town by the N.I.C.E. and living at St. Anne's. Jane is puzzled at first by her status as an equal at the house. Ivy's husband, Tom, is in prison for petty theft.
- Merlinus Ambrosius – The wizard Merlin, awakened and returned to serve the Pendragon and save England. Receives the powers of the Oyéresu. He has been in a deep sleep since the time of King Arthur, and both sides initially believe he will join the N.I.C.E. His appearance at St. Anne's comes as a surprise.
- Andrew MacPhee – A scientist, skeptic, and rationalist, who is a close friend of Dr. Ransom and joins him at St. Anne's. Though not religious, he is deeply influenced by his Presbyterian family background. His uncle was a high official in the Scottish Presbyterian Church, and, allowing for the differences in religious profession, was equally skeptical. He is mentioned parenthetically in Perelandra , and he appears in The Dark Tower . MacPhee, like Ransom, was an officer in the First World War. MacPhee desires to fight the N.I.C.E. with human powers. He is an argumentative character who claims to have no opinions, merely stating facts and illustrating implications. His position in the establishment is to be skeptical, testing every hypothesis and Jane's dreams; however, the awakened Merlin believes MacPhee to be Ransom's "fool" (jester), because MacPhee is "obstructive and rather rude...yet never gets sat on". The character may have been based on William T. Kirkpatrick, former headmaster of Lurgan College and an admired tutor of the young Lewis.
- Mr. Bultitude – Last of the seven bears of Logres, who escaped from a zoo and was tamed by Ransom, who has regained man's legendary authority over the beasts. He is captured by the N.I.C.E., escapes, and destroys the Head.
- Arthur Denniston – An academic at Edgestow and a former friend of Mark Studdock from student days. He and Mark were rival candidates for a fellowship at Bracton College, which Mark won through the influence of Lord Feverstone. They drifted apart before Jane entered the picture and Studdock became obsessed with reaching the "inner circle" at Bracton.
- Camilla Denniston - The wife of Arthur Denniston, very tall and beautiful. She is the first person Jane meets at St. Anne's.
