Jacob Jankowski
The protagonist and narrator, a 93-year-old man reminiscing about his time working as a veterinarian for a circus during the Great Depression when he was 23 years old. He is an ivy-league dropout who joins the circus after a family tragedy.

Marlena
A beautiful equestrian performer who works closely with the animals, especially the elephant Rosie. She is married to the abusive ringmaster August, but falls in love with Jacob.

August
The cruel and paranoid ringmaster who is Marlena's husband. He is extremely possessive of Marlena and violently mistreats the circus animals, especially Rosie the elephant.

Rosie
An elephant that Jacob and Marlena develop a close bond with and train using humane methods, in contrast to August's abuse.

Walter/Kinko
A little person who performs as the clown "Kinko" but is kind-hearted and befriends Jacob; his real name is Walter.

Uncle Al
The unethical but charismatic owner of the Benzini Brothers circus who employs shady business practices.

Camel
An elderly circus worker who looks out for Jacob when he first joins, but later becomes disabled after drinking a toxic substance.