Hiltgunt Margret Zassenhaus (10 July 1916 – 20 November 2004) was a German philologist who worked as an interpreter in Hamburg, Germany during World War II, and later as a physician in the United States. She was honoured for her efforts to aid prisoners in Nazi Germany during World War II.
Hiltgunt Zassenhaus was born in Hamburg to Julius H. and Margret Ziegler Zassenhaus. Her father was a historian and school principal who lost his job when the Nazi regime came to power in 1933. Her brothers were the mathematician Hans (known for the butterfly lemma and the Zassenhaus group), and physicians Günther and Willfried.
Following a bicycling holiday in Denmark in 1933, she decided to study philology, specializing in the Scandinavian languages. She graduated from the University of Hamburg with a degree in Norwegian and Danish language in 1939 and continued her language studies at the University of Copenhagen.
In autumn 1940, Zassenhaus was employed as interpreter at the German office for the censorship of letters. She resigned this job in 1942 and started studying medicine in Hamburg. Later in 1942, she was asked by the prosecutor in Hamburg to censor letters to and from Norwegian prisoners in the Zuchthaus in Fuhlsbüttel, Hamburg. She initially refused, but after further pressure, she accepted on the condition that she be allowed to work independently. Instead of censoring the mail, she added messages urging the recipients to send food or warm clothing.
According to the German prison rules, the prisoners were allowed to receive regular visits, and the Norwegian priests in Hamburg were authorized to visit the prisoners on behalf of their families. She was assigned to interpret for and watch the priests during their visits. Later, she also interpreted for Danish priests and prisoners. She began smuggling in food, medicine, and writing materials. She was aided by the suspicion of the authorities that, because of her position in the Department of Justice, she was a member of the Gestapo.