Lydia Stahl (1890-?) was a secret agent who worked for Soviet Military Intelligence (GRU) in New York and Paris.
She was born Lydia Chkalov in Rostov, in the south of Russia, in 1890. Once the wife of a Tsarist officer, she later married Baron Stahl, a Baltic nobleman, and emigrated to the United States where she became a naturalized citizen. When her only son died in 1918, the lonely and grief-stricken Lydia returned to Europe. She befriended the Finnish writer Hella Wuolijoki and was a regular visitor to her estate Marleback in Southern Finland, which was a meeting place for leftist intellectuals and politicians. Through her relationship with Otto Kuusinen, she met the American radical John Reed, and maintained a correspondence with him until his death in 1920. She joined the Soviet secret service while a refugee in Finland in 1921.
During the 1920s, Lydia established a photography studio in Paris where she copied secret documents for Soviet Military Intelligence. In the spring of 1928 she was transferred to New York to help the GRU resident Alfred Tilton. She remained in New York until 1933, when she returned to Paris to work for the apparatus which included Robert Gordon Switz. Lydia's ami was the French professor Louis Pierre Martin, former attache of the Naval Ministry and member of the Legion of Honor.
In 1933 counterespionage uncovered an apparatus in Finland which included Tilton's wife Maria, Lydia's friend Ingrid Bostrom, and Arvid Jacobson. He provided information which led French counterintelligence to Lydia. She was arrested in December 1933 and other members of the apparatus, including Switz and his wife, were arrested shortly afterward. Lydia was convicted of espionage in April 1935 and served a four-year sentence. She disappeared after her release from French prison.