Mildred Elizabeth Harnack was an American literary historian, translator, and member of the German resistance against the Nazi regime. After marrying Arvid Harnack, she moved to Germany in 1929, where she began her career as an academic. Mildred Harnack spent a year at the University of Jena and the University of Giessen working on her doctoral thesis. At Giessen, she witnessed the beginnings of Nazism. Mildred Harnack became an assistant lecturer in English and American literature at the University of Berlin in 1931.

Arvid Harnack was a German jurist, Marxist economist, Communist, and German resistance fighter in Nazi Germany. Harnack came from an intellectual family and was originally a humanist. He was strongly influenced by Johann Wolfgang von Goethe but progressively moved to a Marxist-Socialist outlook after a visit to the Soviet Union and the Nazis' appearance. After starting an undercover discussion group based at the Berlin Abendgymnasium, he met Harro Schulze-Boysen, who ran a similar faction. Like numerous groups in other parts of the world, the undercover political factions led by Harnack and Schulze-Boysen later developed into an espionage network that supplied military and economic intelligence to the Soviet Union. The group was later called the Red Orchestra by the Abwehr. He and his American-born wife, Mildred Fish, were executed by the Nazi regime in 1942 and 1943, respectively.