Howard Walter Florey, Baron Florey, was an Australian pharmacologist and pathologist who shared the Nobel Prize in Physiology or Medicine in 1945 with Ernst Chain and Sir Alexander Fleming for his role in the development of penicillin.

Sir Alexander Fleming was a Scottish physician and microbiologist, best known for discovering the world's first broadly effective antibiotic substance, which he named penicillin. His discovery in 1928 of what was later named benzylpenicillin from the mould Penicillium rubens has been described as the "single greatest victory ever achieved over disease". For this discovery, he shared the Nobel Prize in Physiology or Medicine in 1945 with Howard Florey and Ernst Boris Chain.