Elizabeth is a well-known, aging fiction author from Australia visiting Appleton College to deliver a series of guest lectures. Rather than discussing her successful literary career, she controversially chooses to speak about animal rights, factory farming, and vegetarianism. She holds strong, deeply felt convictions about animal cruelty that quickly alienate her from her academic hosts and her own family.

John is an assistant professor of physics and astronomy at Appleton College. He tries to keep his familial relationship with the famous novelist Elizabeth Costello a secret to avoid being overshadowed by her fame. He finds himself caught between his mother's controversial animal rights activism and his wife's active hostility toward her presence.

Norma holds a Ph.D. in the philosophy of the mind but struggles to find a permanent teaching position, instead writing academic reviews on primate language experiments. She fiercely opposes Elizabeth's views on animal rights and reasoning. She actively works to prevent Elizabeth from discussing vegetarianism with her children.

Thomas is a large, blond philosophy professor at Appleton College. He represents the traditional, reason-based scientific perspective and actively challenges Elizabeth's views on animal rights. He serves as her primary intellectual opponent during the formal debate at the end of her visit.

Abraham is an academic at Appleton College who protests Elizabeth's first lecture. Offended by her direct comparison of modern animal farming to the Holocaust, he chooses to boycott her dinner party and leaves a written note expressing his outrage.

Elaine works in the English Department at Appleton College. She has studied and written about Elizabeth's literary career and attempts to engage her on topics of human nature and species exploitation during the lecture question-and-answer sessions.

Garrard is the president of Appleton College. During the dinner party in Elizabeth's honor, he attempts to guide the tense conversation by examining the sociological and religious connections to dietary restrictions.

Olivia is the wife of college president Garrard. She participates in the dinner debate about animal rights, arguing that animals are inherently distinct from humans because the two groups do not naturally mix in society.

Wunderlich is a visiting professor from England. At the dinner party, he contributes to the conversation about dietary restrictions by discussing ancient Greek rituals of clean and unclean killing, though he ultimately supports Elizabeth's point about human compassion extending to beings without conscious awareness.

Ruth is a psychology professor at Appleton College. She engages Elizabeth in a conversation about an experiment involving a chimpanzee sorting photographs, finding common ground on the mysteries of animal cognition.

Arendt is a dean at Appleton College who questions the logic of vegetarianism. He points out that the animals being saved by dietary boycotts are completely unaware of the impact, challenging Elizabeth's moral framework.

Marjorie Garber is a professor of English at Harvard who provides an academic reflection on Elizabeth Costello's fictional lectures. She uses her background in gender studies and literary analysis to question whether the lectures are literal arguments for animal rights or an allegory for the value of literature itself.

Peter Singer is a real-world bioethics professor and animal rights activist who responds to the lectures by writing his own piece of fiction. In his reflection, he introduces a fictionalized version of himself debating the ethics of speciesism and animal consciousness with his daughter.

Wendy Doniger is a professor of the history of religion who responds to Elizabeth's arguments. She bolsters Elizabeth's claims by citing Vedic stories, Asian mythologies, and Hindu texts to prove that compassion for animals and vegetarianism have long histories outside of modern Western culture.

Barbara Smuts is a researcher who has spent her career studying wild primates and dogs. She uses her personal experiences living among baboons and chimpanzees to directly challenge the idea that humans and animals cannot form meaningful communities, calling for greater sympathetic connections with nonhuman persons.

Naomi is Peter Singer's daughter in his fictionalized response essay. She challenges her father's utilitarian views on animal rights, accusing him of relying too heavily on reason and speciesism when he argues that animals who cannot conceptualize the future have less valuable lives.