John le Carré (1931-2020), the pen name for David John Moore Cornwell, was a British author whose espionage novels set the standard for the genre. During the 1950s and '60s, he worked for the Security Service and the Secret Intelligence Service, and began writing novels under a pen name. His third book, The Spy Who Came in from the Cold (1963), became an international bestseller. Following the success of this novel, he left MI6 to become a full-time author. Many of his novels have been adapted for film.