Michael Edward Ash (17 December 1927 – 30 April 2016) was a British mathematician and brewer. Ash led a team that invented a nitrogenated dispense system for Guinness stout first released in 1959, which evolved to become the beer now sold globally as Draught Guinness. As the manager in charge of the Easy Serve project, Ash is credited as the inventor of nitrogenated beer (sometimes known as "nitro beer" colloquially). He was Managing Director of Crookes Laboratories (1962–1972) where he was responsible for securing the license for an early anti-depressant in the UK, Prothiaden.