Stasys Antanas Backis (February 10, 1906 – November 10, 1999) was a Lithuanian diplomat.
A graduate of the University of Paris, he became an employee of the Lithuanian Ministry of Foreign Affairs in 1930.
In 1938, he was stationed at the Lithuanian embassy in Paris.
After the occupation of Lithuania by the Soviet Union in June 1940, Lithuanian diplomats did not recognize the new Soviet government and established the Lithuanian diplomatic service that functioned in conditions of exile, continued to represent independent Lithuania, and preserved legal continuity of the state.
After the arrest of ambassador Petras Klimas, Backis actively headed the unofficial Lithuanian embassy in Paris until 1960 when he relocated to Washington, D.C..
After the death of Stasys Lozoraitis, Backis was the chief of the Lithuanian diplomatic service from 1983 to the dissolution of the Soviet Union in August 1991.
Backis was the father of Cardinal Audrys Juozas Backis.