Vincent Marks (10 June 1930 – 6 November 2023) was an English  pathologist and clinical biochemist known for his works on studying insulin and hypoglycemia. His contributions to medical science include simplifying low blood glucose testing, introducing insulin radioimmunoassay, and advancing diabetes research. Marks played an important role in high-profile medico-legal cases, notably providing expert testimony that helped acquit Danish-born British socialite Claus von Bülow in 1985, a case that was the basis of the Oscar-winning movie Reversal of Fortune (1990).
Marks was also a nutritionist who studied intestinal hormones and coined the term muesli belt malnutrition, referring to parents feeding their children what is considered extremely healthy foods, but, in the process depriving them of essential fats.