David James Purslove Barker CBE FRS FMedSci (29 June 1938 – 27 August 2013) was an English physician and epidemiologist and originator of the Barker Hypothesis that foetal and early infant conditions have a permanent conditioning effect on the body's metabolism and chronic conditions later in life. Barker was elected as a Fellow of the Royal Society and a Fellow of the Academy of Medical Sciences in 1998 and was appointed a CBE in 2006. He married twice; firstly to Angela, with whom he had three sons and two daughters, and secondly to Jan.