Ernst-August Köstring (20 June 1876 – 20 November 1953) was a German diplomat and officer who served during World War II.

Born in Imperial Russia in 1876, Ernst August Köstring grew up in St Petersburg (or Moscow[1]) and was fluent in Russian.

During the invasion of Poland, as a German military attaché in Moscow, Köstring played a key role in co-ordination between Nazi Germany and Soviet Union.

[4] On 8 August 1940, Köstring was warned by General Franz Halder that "he would have to answer a lot of questions soon",[2] which made him one of a few people who knew of the invasion of the Soviet Union despite the non-aggression pact.

He visited, together with Friedrich Werner von Schulenburg, prisoner-of-war camps to recruit Soviet prisoners-of-war for the German war effort.