Nathan Witt, born Nathan Wittowsky, was an American lawyer who is best known as being the Secretary of the National Labor Relations Board from 1937 to 1940. He resigned from the NLRB after his communist political beliefs were exposed and he was accused of manipulating the Board's policies to favor his own political leanings. He was also investigated several times in the late 1940s and 1950s for being a spy for the Soviet Union in the 1930s. No evidence of espionage was ever found.