Here are the most significant characters.
Death is the narrator of the book. Death carries away souls after they've died and he is the one telling/remembering Liesel's life story.
Liesel Meminger is the subject of the story, the one who piqued Death's interest. Death calls her "the book thief" because she stole her first book at her brother's funeral. Liesel's father had been taken on charges of communism. Liesel's mother sent her to live with Hans and Rosa Hubermann during WWII.
Hans Hubermann helps Liesel get through her nightmares and teachers her to read, a father/grandfather figure to her.
Rosa Hubermann is harsh but treats Liesel with tough love to protect her.
Rudy Steiner is Liesel's best friend and his crush on her is evident early on.
Max Vandenburg is a Jewish fighter, son of Erik Vandenburg who saved Hans' life. In return, Hans agrees to hide Max in their basement where he bonds with Liesel.
Ilsa Hermann, one of Rosa's laundry clients, allows Liesel to come and read from her library.
Werner Meminger is the name of Liesel's brother who dies on the way to the Hubermann's city of Molching.
Paula Meminger is the name of Liesel's mother.
Frau Diller is a pro-Nazi shopkeeper who faults those who don't do the Nazi salute.
Hans Hubermann Jr. is Hans' son. Hans Junior is a Nazi sympathizer and stops returning home for holidays because he disagrees with his father's sympathies toward the Jews.
Some other appearing or mentioned characters are (there are too many to mention them all): Tommy Muller, Frau Holtzapfel, Trudy Hubermann, Franz Deutscher, Arthur Berg, Viktor Chemmel, Walter Kugler, Frau Heinrich, Sister Maria, Ludwig Schmeikl, Heinz Hermann, Johann Hermann, Michael Holtzapfel, Robert Holtzapfel, Reinhold Zucker, Fritz Hammer, Alex Steiner, and Otto Sturm.