Denis Geoffrey Oswald (12 November 1910 – 5 February 1998) was an English first-class cricketer, educator and a codebreaker at Bletchley Park.

Oswald was born at Stanley in the Falkland Islands to Louis and Lillian Oswald. He left the Falklands for England with his family when he was 8 years old aboard the SS Inca.^[1] He was educated in England at St Lawrence College, Ramsgate, before going up to Wadham College, Oxford.^[2] While studying at Oxford, he made two appearances in first-class cricket for Oxford University in 1931, playing against Leicestershire and the touring New Zealanders at Oxford.^[3] In addition to playing first-class cricket, Oswald also played minor counties cricket for Hertfordshire in 1931 and 1932, making a total of nine appearances in the Minor Counties Championship.^[4] After graduating from Oxford in 1932, Oswald took up the post of languages teacher at Uppingham School.^[5]

Oswald served in the Intelligence Corps during the Second World War, initially as a private. He was commissioned as a second lieutenant in June 1941.^[6] In Autumn 1942, Oswald, alongside Ralph Tester, Jerry Roberts and Peter Ericsson, founded the Testery section at Bletchley Park.^[5]

• Denis Oswald at ESPNcricinfo