Alexander Fleming (1881–1955)

Born in Scotland, Fleming moved to London as a teenager and later qualified as a doctor. He was researching influenza (the ‘flu’) in 1928 when he discovered penicillin. This was then further developed into a usable drug by the scientists Howard Florey and Ernst Chain. By the 1940s it was in mass production. Fleming won the Nobel Prize in Medicine in 1945. Penicillin is still used to treat bacterial infections today.