Sir David Allan "Dai" Rees, FRS[4] (28 April 1936 – 10 June 2021)[5] was a British biochemist and science administrator who was chief executive of the Medical Research Council between 1987 and 1996.

[2] Rees was born in Silloth, Cumberland[5] but educated in Wales: he attended Hawarden Grammar School[2][6] and received his BSc and PhD degrees in chemistry from University College of North Wales, Bangor.

[7] Rees was a lecturer in chemistry at the University of Edinburgh from 1960 until 1970, researching carbohydrate conformation and structure.

He left in 1982 to become director of the National Institute for Medical Research before serving as chief executive of the Medical Research Council from 1987 to 1996.

[5] Rees received a DSc degree from the University of Edinburgh in 1969.