Nahum Isaakovich Eitingon (Russian: Наум Исаакович Эйтингон Naum Isaakovič Ejtingon), also known as Leonid Aleksandrovich Eitingon (Russian: Леонид Александрович Эйтингон) (6 December 1899, Shkloŭ, Mogilev Governorate – 3 May 1981, Moscow), was a Soviet intelligence officer, who gained prominence through his involvement in several NKVD operations, including the assassination of Leon Trotsky, the orchestration of partisan movements during World War II, and atomic espionage. He has been described by Yevgeny Kiselyov as one of the organisers and managers of the state terrorism system under Joseph Stalin and later a victim thereof. He was the great-cousin of Max Eitingon.