Leonard George Goodwin was a British protozoologist noted for his work on testing the effectiveness of chemical compounds in treating tropical diseases. He was educated at William Ellis School before being accepted into University College London to study botany and zoology. After graduating he went to the College of the Pharmaceutical Society and studied pharmacy, graduating in 1935. He became a demonstrator at the college under J H Burn and at his urging took further degrees in medicine and physiology.
The start of World War II saw the College evacuated, leaving Goodwin to find a new job. He started work at the Wellcome Bureau of Scientific Research but was called up for military service with the Royal Tank Regiment soon afterwards. After only a few days of training he was returned to Wellcome to work on tropical diseases, something considered 'vital war work' which excused him from military service. One of the important problems he was dealing with at the time was trying to find a way of preventing troops being infected with leishmaniasis, which was affecting large numbers of troops in Sicily at the time.
He continued working at the Wellcome Bureau of Scientific Research until 1958, when he became director of the Wellcome Laboratories of Tropical Medicine. In 1964 he became head of the Nuffield Laboratories for Comparative Medicine, staying there until 1980. During this time he conducted research into anticoagulants, trypanosomiasis and arteriosclerosis.
In 1976 he was elected a Fellow of the Royal Society, and in 1977 New Year Honours was appointed Companion of the Order of St Michael and St George "for services to the study of tropical diseases."