In Neal Stephenson's novel Cryptonomicon, Rudolf von Hacklheber, or Rudy as many people call him, is a homosexual German mathematician. Rudy is a friend to Lawrence Pritchard Waterhouse and Alan Turing while he is studying at Princeton before World War II. In the beginning of the book, he and his other two mathematically inclined friends enjoy bicycling and camping while discussing advanced mathematics, including but not limited to Gödel, Liebniz, Principia Mathematica, cryptology, and designs, concepts, and abstract ideas about mechanical computation devices.

Later, Turing graduates and Waterhouse heads back to his home state once his year-long scholarship runs out to finish school. Rudolf himself, however, is called back to Germany to assist in the war effort. Rudy isn't a fan of the Third Reich or the Nazi Party, and finds Hitler to be apalling in and of himself.

Fortunately, Herr von Hacklheber's mathematical expertise lands him an important job in the government, including prewar work under Karl Dönitz at the Beobachtung Dienst of the Kriegsmarine, and later was moved to Referat Iva of Gruppe IV, which was part of Hauptgruppe B, Cryptananlysis, and thoroughly confuses and tortures Bobby Shaftoe with even more detail concerning the structure of the Third Reich, especially with words like "Wehrmachtnachrichtungenverbindungen" and other (unspecified in the book) incredibly long German compound words. While a character of great import to the plot, Herr von Hacklheber is in a surprisingly small number of pages himself. It is important to note, while some characters in this novel are not fictional (i.e. Alan Turing and Lieutenant Ronald Reagan), the vast majority of them (i.e. Randy Waterhouse, Rudolf von Hacklheber, Enoch Root) are completely fictitious.