Jonas Henrik Kellgren (11 September 1911 – 22 February 2002) was a British physician and the first professor of rheumatology in the United Kingdom at the University of Manchester.
He was an expert adviser to the World Health Organization and earned a Canada Gairdner International Award for his work.
He also studied in Scandinavia on a scholarship and at St George's, University of London alongside his brother Ernst.
After the war in 1946, Kellgren resumed his pain research and experiments at Wingfield Morris Hospital in Oxford, with a focus on peripheral nerve injuries.
Kellgren conceptualised nodal osteoarthritis, characterised by nodes on the distal joints on the fingers and other parts of the body, often genetic and found in older women.
A member of a number of organisations and committees, Kellgren was named an expert advisor to the World Health Organization in 1961 and joined the Manchester Regional Hospital Board in 1965.
He married his second wife, Thelma Reynolds, an American nurse from Amesbury, Massachusetts, in 1942 in St Marylebone.