Double Agent Juan Pujol Garcia (Garbo)

Spanish citizen Juan Pujol Garcia managed to convince the Germans he was a fanatical Nazi, then convinced the British he was a valuable spy, then played BOTH sides simultaneously. He created a fictional network of 27 sub-agents that didn't exist, fabricated detailed reports about Allied operations, and so impressed the Germans that they awarded him the Iron Cross. The British knighted him with the Order of the British Empire, making him the only person in history to receive both the Iron Cross and an OBE. His misinformation about the D-Day invasion location was instrumental in keeping German forces at Calais.