Andrew Melvin Ramsay (1901–1990) was a British physician, who is known for his research and advocacy on myalgic encephalomyelitis (ME), a chronic disease causing muscle weakness and cognitive dysfunction. Ramsay worked as a consultant at the Royal Free Hospital in London during a mysterious 1955 disease outbreak of what later became known as ME. He studied the disease and similar outbreaks elsewhere. Work by Ramsay showed that although ME seldom caused death, the disease could be highly disabling.
Upset by the lack of sympathy for long-term sufferers, he became their lifelong advocate and co-founded the ME Association. In 1986 he published the first case definition of ME. Two research grants are named after him: the Ramsay research grant from the Solve ME/CFS Initiative and the Ramsay Research Fund of the ME Association.