Karl is a fourteen-year-old boy living in Berlin who desires to be a cartoonist. Despite coming from an agnostic, culturally assimilated family and possessing physical traits that do not match Nazi stereotypes, he becomes a target for anti-Semitic bullying. He views boxing as a way to defend himself and manage his increasingly restrictive environment.

A real-life former heavyweight champion boxer revered in Germany. He acts as an elusive mentor figure to Karl, bartering boxing lessons for a painting from Karl's father. He maintains a complex public persona, attempting to balance his celebrity status and the favor of Nazi officials with his ties to the Jewish community.

Karl's father is a proud, independent art gallery owner and World War I veteran. He favors subversive, abstract expressionist art but is forced to sell bland landscapes due to Nazi prohibitions. He holds a cosmopolitan outlook, considers himself a German patriot, and stubbornly attempts to maintain his individuality.

Karl's mother is a woman who once harbored artistic ambitions before focusing on her family. She struggles with bouts of severe depression, often retreating to her bed or a hot bath, but possesses strong maternal instincts and quick perception regarding the rising dangers in Berlin.

Karl's younger sister is a small, pale, near-sighted girl who internalizes the anti-Semitism around her and considers herself ugly. She feels isolated and lonely, finding some solace in the *Winzig und Spatz* comic strips that her brother draws for her.

A transvestite living in Berlin who hires the Sterns to print flyers for underground parties. She possesses an emotional courage that allows her to maintain her flamboyant identity despite the immense risks of the current regime, and she harbors a longstanding connection to Karl's father.

Rebecca Stern's younger brother. He is involved in subversive, underground communist activities against the regime, causing tension within the Stern family regarding their overall safety.

A gentile girl living in the Sterns' apartment building who dreams of moving to France to study music. She shares a flirtatious, complicated dynamic with Karl that must remain hidden due to the increasing racial laws and her father's strict rules.

The tallest member of the "Wolf Pack," a gang of Nazi-sympathizing school bullies. He orchestrates attacks against Jewish students and represents the normalization of brutal anti-Semitism among German youth.

The smallest and least imposing member of the Wolf Pack. He initially fights Karl one-on-one, displaying a cowardice that vanishes only when his opponent begins to weaken.

A member of the Wolf Pack bullies at Karl's school who actively participates in humiliating and physically assaulting Jewish students.

A giant, gentle janitor at the boxing club who speaks with a stutter. He is a former boxer whose career ended after an eye injury caused by bullies, and he bonds with Karl over a shared love of American comics.

The Polish proprietor of the Berlin Boxing Club. Though he possesses a sharp tongue and a gruff exterior, he provides a training ground for Karl and employs Neblig despite his speech defect.

The superintendent of the Stern family's apartment building. He is a vocal Nazi sympathizer who proudly displays a swastika flag on his door and reads vicious anti-Semitic propaganda magazines.

Karl's science and history teacher. He attempts to stick to neutral scientific facts rather than Nazi racial propaganda and genuinely cares about Karl's well-being, though he possesses little power to protect his Jewish students.

One of Karl's casual gentile school friends. His gradual acceptance of the new regime and decision to join the Hitler Youth illustrates the passive conformity of average citizens.

A gentile classmate of Karl's who, like Kurt, views the encroaching Nazi regulations as boring school rules rather than a threat, eventually joining the Hitler Youth.

The newly appointed, Nazi-affiliated principal at Karl's school. He enforces regulations that purge the library of Jewish authors and mandates Hitler Youth participation.

The trusted, long-time housekeeper for the Stern family. She cares deeply for the children but is eventually forced to leave her employment due to the family's financial struggles and new racial laws.

A Jewish proprietor of a local art supply store. He sells Karl his drawing materials and maintains his dignity despite increasing despair and targeted harassment from Nazi youths.

A courtly, middle-aged policeman and old army friend of Sigmund Stern. He tries to assist the family discreetly by passing along information from inside the police force.

A famous Czech actress and the wife of boxing champion Max Schmeling. She accompanies him to social events and shares in his celebrity lifestyle in Berlin.