- The protagonist of the book. Douglas is a twelve-year-old boy with a vivid imagination and a compassionate nature. He cares deeply about his family and his friends, and he wants to understand the events that transpire around him. Douglas has trouble understanding why things do not always work out well, and death is particularly troublesome to him. His passion for life and his ability to clearly elucidate it are rare traits for a twelve-year-old child. Douglas possesses a deep understanding of life, and this is precisely why it is so difficult for him to come to terms with the concept of death. However, Douglas is an avid learner, and he takes to heart the lessons that he learns from his family members and his friends.
- Douglas's ten-year-old brother. Tom in many ways provides a foil to his older brother. Tom is not yet faced with some of the challenges of growing up that Douglas must go through. His responses to situations help Douglas maintain a balance between taking an adult perspective and seeing things from a child's point of view. Tom is extremely intelligent and very imaginative. He understands Douglas extremely well, even if he cannot always relate to what Douglas is dealing with. Tom sees things that other characters in the book do not see, and he is aware of that fact.
- Douglas and Tom's grandfather. Grandpa Spaulding provides much of the wisdom that Douglas and Tom depend on throughout the novel. He is a witty old man who delights in the beauty of life and the world and has the ability to make his feelings transparent to both adults and children. Grandpa Spaulding is the head of the family, and everyone in the town likes him. He loves to philosophize, and justifies lawn mowing as a great activity because it allows a person to be alone with himself and the world. Grandpa Spaulding finds pleasure in the little things—like dandelions.
in-depth analysis of Grandpa Spaulding.
- Douglas and Tom's grandmother. Grandma Spaulding shares the same zest for life as Grandpa Spaulding and the rest of the family. However, unlike her husband, she has a specific ability that demonstrates how in tune she is with the world—her cooking. Grandma Spaulding is a brilliant spontaneous chef, capable of concocting magnificent feasts without any concept of the specific ingredients. She is a woman who is at home in the world and content with her life and her cooking reflects that security and contentedness.
- The matriarch of the Spaulding family. Great-grandma Spaulding lives like the rest of the family. She is happy with the world and the life that she has lived and she dies contentedly. She tries to pass on to Tom and Douglas her understanding of life as a process that must end even though people live on in their families.
- Douglas's best friend. John Huff is the best athlete among the boys. He is also kind and knows all of the things that twelve-year-old boys want to know. John worries that he will be nothing more than a forgotten memory once he leaves Green Town.
- A very old man whose body has failed him, Colonel Freeleigh lives for the moments when his heart throbs in his chest and his breath comes in gasps. He wants nothing more than to live life to its fullest, and he passes on that passion to the boys through the stories he tells them.
- Douglas and Tom's father is a man at ease among civilization and wilderness. He is quiet and thoughtful, and he understands his children very well. He knows what it is like to grow up and is ready to help Douglas and Tom as they go through the process.
- Strong-minded yet kind, Douglas's mother cares greatly for her children. She is very concerned for their safety and worries that some harm may come to Douglas while he is off in the wilderness with John Huff and Charlie Woodman.
- The town junkman. Mr. Jonas is a caring man who understands what Douglas is going through during his fever. Mr. Jonas himself feels sadness at the ways of the world and knows that loving life is the only way to get past those feelings.
- A boarder in Douglas's grandparents' house. Bill gets along very well with everyone. Grandpa Spaulding teaches him the beauty of mowing a lawn. Bill spends several weeks enchanted with Helen Loomis before she dies, and her keen, inquisitive mind is a match for his.
Miss Helen Loomis
- The ninety-five-year-old Helen Loomis has a lifetime of adventures and a belief in true love that she shares with Bill Forrester. She believes that the love that they share, that of the mind, is the greatest love, and that someday some version of the two of them will meet at the right time and share a lifetime of love.
- Douglas's other good friend. Charlie is the one who introduces the boys to Colonel Freeleigh. Charlie is always looking for thrills and adventure and he has a nose for the magical things that twelve-year-old children need.
- Unwilling to let the mania surrounding the Lonely One scare her, Lavinia Nebbs will not let fear dictate her life. She starts the evening rational and fearless but is reduced to panic on the walk home when she admits her fear. At her house, she stabs and kills the Lonely One with a pair of sewing scissors.
- The antagonist in the book. The Lonely One is a force that everyone in the town fears. The adults fear the man whom Lavinia Nebbs stabs and kills, but the children fear something different. For the children the Lonely One represents the evil force that always lurks in the dark and can never be killed.
- The town inventor. Leo Auffmann is as happy as he is brilliant. On a farcical suggestion from Douglas and Grandpa Spaulding he decides to build a Happiness Machine, but finds that it only threatens the real happiness in his life—his family. He is devoted to his family and could not be any happier than when with his wife and children.
- The wife of Leo. She counsels against Leo's creation of a Happiness Machine by pointing out that all is well in their lives. She understands from the beginning that true happiness comes from a loving family, and Lena does her best to help her husband see this.