Maksymilian Ciezki ([maks?'miljan 't??j?~?ki] (listen); Samter, Province of Posen (now Szamotuly, Poland), 24 November 1898 – 9 November 1951 in London, England) was the head of the Polish Cipher Bureau's German section (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, Ciezki escaped to France to continue work on breaking Enigma ciphers.
In 1943 he was captured by the Germans and interned in an S.S.