Alan Mathison Turing was an English mathematician, computer scientist and code breaker, and few scientists have had as much of an impact on modern technology than he. Turing formalized concepts of computing and algorithms with his 'Turing Machine', an early predecessor of the computers of today. In addition to that, Turing served as a codebreaker in WW II, and it's said his work provided vital intelligence to the good guys. Turing died at the young age of 42, but accomplished so much in his lifetime.
"A computer would deserve to be called intelligent if it could deceive a human into believing that it was human."