Ann Burden
The protagonist of the story, Ann Burden is a 16-year-old girl living in Burden Valley, a valley named after her family as one of the initial inhabitants of the land. Ann is a very strong, self-sufficient girl who lives on her own after her family perishes in the dead world beyond the valley. The book is written as though it is Ann's journal which she has kept since the disappearance of her family. Entries include information about Ann's daily life and experiences, including her first spotting of Mr. Loomis. Her loneliness makes her particularly vulnerable to the adversity that Mr. Loomis shows towards her. She makes attempts at reconciliation, but ultimately fails because of Mr. Loomis' uncompromising and possessive character. In general, she is compassionate, adept, and resourceful. She eventually leaves the valley in search of other people and to pursue her dream of becoming a teacher.
John Loomis
The primary antagonist of the story, John Loomis is a Cornell-trained scientist who helped create the "safe suit," the radiation-proof suit that he wore in order to get to Burden Valley, and the same suit that cost his associate Edward his life. Upon reaching the valley, Mr. Loomis bathes in a radioactive stream and comes down with intense radiation sickness, which Ann helps him through as best as she can. After Loomis recovers from his sickness, he becomes quite insane and begins attacking Ann, causing her to flee to the surrounding woods. He becomes aggressive, insensitive, hostile, and erratic in his behavior towards Ann. After he tries to rape Ann, he makes multiple attempts to capture her after she has run away. As the book comes to a close, Ann abandons Mr. Loomis in the valley, taking his safe suit and going out to the dead lands beyond the valley.
Faro
Faro is Ann's brother's dog. He left when Ann's family disappeared, but then returned after quite a while. He plays a large role in the book as he is essentially Ann's last hope. At one point, he inadvertently aids Loomis in hunting for Ann, primarily because he wishes to be with Ann as she is a familiar face and smell. Faro ends up dying when he falls in Burden Creek and contracts horribly fast-moving radiation sickness.
Ann's Mother, Father, and Brother
At the beginning of the story, we learn that Ann's entire family left in search of others who had survived the bombing. However, they all die of radiation sickness shortly after their departure. Not much is said about any of them in the rest of the story.
Edward
Edward is a scientist as well as associate of Mr. Loomis that worked with him at the Ithaca-based government laboratory developing radioactive safe suits before the war. Mr. Loomis kills him because Loomis fears that Edward is going to steal the only safe suit ever produced (in order to search for life outside the laboratory), the only thing that can protect anyone from the deadness. Though Mr. Loomis does not reveal the backstory of Edward, Ann picks it up from the conversations that Mr. Loomis has with him in his nightmares. Edward looms in the background as a quasi-mythical figure that represents to Ann what Mr. Loomis is capable of doing, as well as what he has done.
