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. Throughout ‘The Time Quintet’, Calvin grows affection and friendship with the Murry family, specifically Charles Wallace and Meg, although it is stronger with the latter.