Maksymilian Ciężki (1899 in Samter, Province of Posen – November 9, 1951; ) was the head of the German section of the Polish Cipher Bureau (BS–4) in the 1930s, during which time (from December 1932) the Bureau decrypted German Enigma messages. During the German invasion of Poland in September 1939, Ciężki escaped to France to continue work on Enigma ciphers, and in 1943 was captured by the Germans and interned in an SS concentration camp.