Elżbieta Zawacka (; 19 March 1909 – 10 January 2009), known also by her war-time nom de guerre Zo, was a Polish university professor, scouting instructor, SOE agent and a freedom fighter during World War II. She was also a Brigadier General of the Polish Army (the second and last woman in the history of the Polish Army to hold this rank), promoted by President Lech Kaczyński on May 3, 2006. The only woman among the Cichociemni, she served as a courier for the Home Army, carrying letters and other documents from Nazi-occupied Poland to the Polish government in exile and back. Her regular route ran from Warsaw through Berlin and Sweden to London. She was also responsible for organizing routes for other couriers of the Home Army.