Jimmy is an imaginative, linguistically inclined young man who grows up feeling alienated within highly secure corporate research compounds. In the devastated present, he adopts the moniker Snowman, scrounging for survival while serving as a reluctant caretaker to a new humanoid species. He relies on reciting obsolete vocabulary words to retain his sanity and distract himself from his isolation.

Glenn is a brilliant, highly logical student who adopts the handle Crake while playing an online game called Extinctathon. He excels at science and views human emotions, reproduction, and natural limitations as biological inefficiencies. He operates with extreme pragmatism, focusing his energy on genetic engineering and corporate projects aimed at solving overpopulation.

Oryx is a young woman who endures extreme exploitation after being sold from her impoverished village as a child. Despite her traumatic early years in trafficking and the underground adult industry, she maintains a serene, practical outlook on life. She eventually works in a high-level corporate facility, teaching botany and zoology to genetically engineered beings.

The Children of Crake are a group of genetically engineered, aesthetically perfect humanoids designed to replace flawed humanity. They possess unique biological traits, such as self-healing purring, rapid maturation, and an innate lack of jealousy or aggression. They live a simple, peaceful existence, largely unaware of the history of the world before their creation.

Jimmy's parents are corporate scientists working in high-security genetic engineering compounds. The father is a pragmatic genographer focused on climbing the corporate ladder, while the mother, Sharon, is a microbiologist who becomes deeply depressed over the ethical implications of their work. Their frequent arguments and ideological divide create a highly unstable household.

Ramona is a lab technician and colleague of Jimmy's father who eventually moves in with the family after Jimmy's mother leaves. She is a practical, straightforward woman who adapts easily to the sterile, secure life within the corporate compounds.

The Survivors are a small group of three gaunt, disheveled individuals who appear near Snowman's encampment. Their sudden appearance challenges Snowman's belief that he is the last remaining human, presenting a mysterious new variable in his isolated existence.

Uncle En is a trafficker who purchases children from impoverished villages and herds them to the city. He operates with ruthless opportunism, forcing his captives to sell flowers and luring men into extortion schemes in hotel rooms.

Abraham is the designated leader among the Children of Crake. Like the rest of his kind, he is physically perfect and entirely non-aggressive, acting primarily as a spokesperson for the group when they need to communicate with Snowman.