Meg Murry is a high school student, a defensive misfit who gets along best with her family and her new friend Calvin O'Keefe. She wears glasses, has had dental braces and has "mouse-brown" hair, and initially considers herself "repulsive-looking" and "dumb", although she is quite good at math. By the time of A Wind in the Door, Meg is much happier in school than previously, in part because of her friendship with Calvin, but is deeply worried about Charles Wallace. In "Naming" Mr. Jenkins, Meg learns to love and appreciate someone she has always resented. In the course of the story Meg also learns to "kythe" with Calvin, Proginoskes, and others, communing with them essentially by telepathy.
Charles Wallace Murry is noted as being extremely intelligent, and a telepath as well. He is something new and different, biologically and "in essence" according to his mother. He is usually the first to discover certain elements important to the books, including the singular cherubim Proginoskes. Charles Wallace is bullied by fellow children and misunderstood by adults outside his family. He recognizes that this is a problem he must solve himself; that like any new lifeform, he must learn to adapt successfully to his environment in order to survive. Charles has blue eyes, and is said to be small for his age.
Calvin O'Keefe is tall and skinny, with orange hair, freckles and blue eyes, and is a popular boy on the basketball team. As of A Wind in the Door, he is already a high school senior at the age of fifteen, and class president. However, he did not feel that anyone understands or cares about him until he became friends with the Murry family. He is the third eldest child of Paddy and Branwen O'Keefe, who have eleven children and are seemingly neglectful of all of them. Calvin considers himself a biological "sport" and different from the rest of his family. Being poor, the O'Keefes are unable to afford new clothes to accommodate Calvin's growth spurts, and he often wears clothes that are too short for him. Calvin tells Meg that one point in seventh grade he had to make do with women's Oxford shoes that were much too small for him and consequently he cut off the toes of them along with the heels. The school principal, Mr. Jenkins, bought him new ones, carefully scuffing them first to make them appear used. Later Calvin earned enough money in summer jobs to buy his own shoes and other necessities.
Mr. Jenkins, another character from A Wrinkle in Time, is further developed in Wind. Formerly the high school principal, Mr. Jenkins has become the principal of Charles Wallace's elementary school instead, an apparent demotion. He is described as having dandruff, thinning mouse-brown hair and smelling of "old hair cream," and Meg thinks of him as a failure and an obstacle. However, later in the book Meg respects the often overlooked man.
Proginoskes, a new character, is a "singular cherubim" who seems to resemble a Seraph; he becomes a particular friend of Meg's. "Progo" has what seems like hundreds of constantly moving wings, a great quantity and variety of eyes (which Meg seems to travel through at some points in the book), and "jets of flame" and smoke. He does not always take material form, and even when he does, as he tells Meg, not everyone is able to see him. Like Meg, Proginoskes is a Namer, and once learned the names of all the stars. The character's own name means "foreknowledge". He teaches and helps Meg kythe, which is a form of telepathy.