Hillel Katz (born 24 September 1905 in Cieszyn, Austro-Hungarian Empire) was a Jewish Communist, who was an important member of a Soviet espionage network in occupied France, that the German Abwehr intelligence service later called the "Red Orchestra" ("Rote Kapelle").

[1] In the role of an underground executive and recruiter,[2] he acted as both secretary and assistant to Leopold Trepper and liaised between Léon Grossvogel and Henry Robinson in matters relating to the running of the French covert black market trading company Simex.

[4] When he moved to Paris, Katz concealed his Jewish origins and legalised himself as a Frenchman under the name Andre Dubois.

[2] Katz was particularly interested in educational reform, specifically in the modern and anti-authoritarian approach advocated by Célestin Freinet as well as the works of Maria Montessori.

He was captured and taken prisoner in June 1940 during the German advance, but managed to escape with Aldred Corbin by swimming across the River Somme.

[13] Trepper allegedly gave up the names and addresses of most of the members of his own network,[14] the first people he betrayed were Katz and Grossvogel.

[16] Katz was moved to a house belonging to Karl Bömelburg at 40 boulevard Victor Hugo, Neuilly-sur-Seine at Trepper's insistence.