Jerzy Witold Różycki (pronounced [ˈjɛʒɨ ruˈʒɨt͡ski] ⓘ; 24 July 1909 – 9 January 1942) was a Polish mathematician and cryptologist who worked at breaking German Enigma-machine ciphers before and during World War II.

From September 1932 Różycki served as a civilian cryptologist with the Polish General Staff's Cipher Bureau, housed till 1937 in Warsaw's Saxon Palace.

He worked there together with fellow Poznań University mathematics alumni and Cipher Bureau cryptology-course graduates Marian Rejewski and Henryk Zygalski.

Their son, Janusz Różycki, born May 10, 1939, completed his studies at the Academy of Fine Arts in Warsaw and went on to be a member of the Polish fencing team that won a silver medal at the 1964 Tokyo Olympics.

[3] On 21 February 2000, Polish President Aleksander Kwaśniewski posthumously awarded Różycki the Grand Cross of the Order of Polonia Restituta for outstanding contributions to his homeland.

On 5 August 2014 the Institute of Electrical and Electronics Engineers (IEEE) honored Rejewski, Różycki, and Zygalski with its prestigious Milestone Award, which recognizes achievements that have changed the world.