Charles Wallace
The main character of the novel, Charles Wallace, has a gift for traveling through time, and after a threat of nuclear war arises, he is urged by Mrs. O'Keefe to go on a time-traveling journey to prevent the disaster. His prayer at the magical stones summons a magical unicorn with wings that will help him and protect him on his journey.
Gaudior
Gaudior is the winged unicorn that appears before Charles Wallace after he sings the prayer. He is sent to help Charles Wallace save the world by traveling through time and influence the present to prevent the nuclear war.
Meg
Meg is Charles Wallace's sister who is present throughout his journey through their mind connection, the so-called "kything". She makes sure that he is safe, and gives him information that he needs from the present.
Mrs. O'Keefe
Meg's mother-in-law, Mrs. O'Keefe, is an old woman who unknowingly shares the prayer from her Irish ancestors with Charles, that will help him save the world. The novel reveals her background and the reason for her cold and distant nature.