Alexander Fleming was 73 years old when he died.
Fleming was born on 6 August 1881 and died on 11 March 1955, so he had not yet reached his 74th birthday. He died in London after a heart attack, ending the life of the Scottish physician and microbiologist best known for discovering penicillin.
His age is sometimes confused with dates associated with his discoveries and honours. Fleming observed the antibacterial effect of mould in 1928, when he was 47, and shared the Nobel Prize in Physiology or Medicine in 1945, when he was 64.
Fleming’s death came sixteen years before modern genetic analysis clarified the identity of his original penicillin-producing strain. His ashes were later buried in St Paul’s Cathedral, London, reflecting his importance in British scientific history.