Britain / UK: Alan Turing (1912-1954), computer scientist and cryptologist instrumental in breaking Germany's 'enigma' machine code during World War II, c. 1947

Alan Mathison Turing was a British pioneering computer scientist, mathematician, logician, cryptanalyst, philosopher, mathematical biologist, and marathon and ultra distance runner. He was highly influential in the development of computer science. During the Second World War, Turing worked for the Government Code and Cypher School at Bletchley Park, Britain's codebreaking centre. Turing's pivotal role in cracking intercepted coded messages enabled the Allies to defeat the Nazis in many crucial engagements, including the Battle of the Atlantic; it has been estimated that the work at Bletchley Park shortened the war in Europe by as many as two to four years. Turing was prosecuted in 1952 for homosexual acts, when such behaviour was still criminalised in the UK. He accepted treatment with oestrogen injections (chemical castration) as an alternative to prison. Turing died in 1954, 16 days before his 42nd birthday, from cyanide poisoning. An inquest determined his death a suicide, but it has since been noted that the known evidence is equally consistent with accidental poisoning. In 2009, following an Internet campaign, British Prime Minister Gordon Brown made an official public apology on behalf of the British government for 'the appalling way he was treated'. Queen Elizabeth II granted him a posthumous pardon in 2013. (Photo by: Pictures From History/Universal Images Group via Getty Images)