Lt. Col. Karol Gwido Langer (Zsolna, Austria-Hungary, 2 September 1894 – 30 March 1948, Kinross, Scotland) was, from at least mid-1931, chief of the Polish General Staff's Cipher Bureau, which from December 1932 decrypted Germany's military Enigma-machine ciphers.
Poland's prewar achievements paved the way for Britain's World War II Ultra secret.