The novel is divided into three books. The main characters in each book are:
- Oskar Matzerath: Writes his memoirs from 1952 to 1954, age 28 to 30, appearing as a zeitgeist throughout historic milestones. He is the novel's main protagonist and unreliable narrator.
- Bruno Munsterberg: Oskar's keeper, who watches him through a peep hole. He makes knot sculptures inspired by Oskar's stories.
- Anna Koljaiczek Bronski: Oskar's grandmother, conceives Oscar's mother in 1899, which is when his memoir begins.
- Joseph Koljaiczek ("Bang Bang Jop" or "Joe Colchic"): Oskar's grandfather, a "firebug".
- Agnes Koljaiczek: Kashubian Oskar's mother.
- Jan Bronski: Agnes' cousin and lover. Oskar's presumptive father. Politically sided with the Poles.
- Alfred Matzerath: Agnes' husband. Oskar's other presumptive father. Politically sided with the Nazi Party.
- Sigismund Markus: A Jewish businessman in Danzig who owns the toy store where Oskar gets his tin drums. The store is ruined during the Danzig Kristallnacht.
- Maria Truczinski: Girl hired by Alfred to help run his store after Agnes dies and with whom Oskar has his first sexual experience. She becomes pregnant and marries Alfred, but both Alfred and Oskar believe that they are Maria's child's father. She remains Oskar's family throughout the post-war years.
- Bebra: Runs the theatrical troupe of dwarfs which Oskar joins to escape Danzig. He is later the paraplegic owner of Oskar's record company.
- Roswitha Raguna: Bebra's mistress, then Oskar's.
- "The Dusters": Danzig street urchins gang, Oskar leads as "Jesus" after he proves his mettle by smashing all the windows with his voice at the abandoned Baltic Chocolate Factory.
- (Sister) Dorothea: A nurse from Düsseldorf and Oskar's love after Maria rejects him.
- Egon Münzer (Klepp): Oskar's friend. Self-proclaimed communist and jazz flautist.
- Gottfried Vittlar: Friends with and then testifies against Oskar in the Ring Finger Case at Oskar's bidding.