Atomic Spy: The Dark Lives of Klaus Fuchs is a 2020 biography of Klaus Fuchs, a so-called atomic spy, by Nancy Thorndike Greenspan. The book was published by Viking Press and received several reviews. Fuchs was a physicist who is best known for passing secrets from the Manhattan Project to the Soviet Union during World War II. The book paints a sympathetic picture of Fuchs, ultimately arguing that his crime was done with good intentions, for "the betterment of mankind". Though several reviews noted their opposition to this conclusion and the sympathy the book shows to Fuchs, it has received mostly positive reviews.