Alan Turing is the newest face of the £50 note.
Turing, who was named the most "iconic" figure of the 20th Century earlier this year, will be on the new design of the Bank of England's note.
This will be the final banknote to move from paper to polymer and people will be able to start using it by the end of 2021.
Find out more about him below.
Alan Turing was a mathematician who cracked codes during World War Two. It is thought that Turing and his fellow code-breakers shortened the war by several years.
He worked for the British Government's Code and Cypher School before World War Two broke out.
In 1939, he began working at Bletchley Park in Buckinghamshire, where top secret work was carried out to crack Germany's military codes.
Turing's main job at Bletchley was to crack something called the 'Enigma' code. The Enigma was a type of machine used by the German army to send secret messages.
Turing and another code-breaker called Gordon Welchman invented a machine known as the Bombe. This device helped to significantly reduce the work of the code-breakers.
During his life, he worked almost entirely in secret and it wasn't until long after his death that the legacy of his life and work came to light. His war-time efforts had a huge influence on the development of computer science and artificial intelligence.
Turing died on 7 June 1954.
Today he is the most celebrated figure of the 20th Century, a father of computing, war hero and genius.
Alan Turing was gay and, in 1952, he was arrested because of this. Being homosexual was illegal in Britain at this time.
In 2013, he was pardoned for this 'crime'. Being pardoned after death is called being posthumously pardoned.
In 2017, the government agreed to officially pardon men accused of 'crimes' like this, meaning they will no longer have a criminal record.
This pardoning has come to be known as the Alan Turing law.