Name at birth: Margaret Hilda Roberts

Margaret Thatcher was the United Kingdom's first woman prime minister. She held the office of PM for 11 years -- longer than anyone in the 20th century. Thatcher attended Somerville College, Oxford, where she earned a chemistry degree (1947) and was president of the student Conservative Association. In the 1950s she trained as a lawyer and then was elected to Parliament as the member for Finchley in 1959. Her reputation as a rock-ribbed conservative grew over the next two decades, and she was named prime minister on 4 May 1979. Thatcher shored up a Conservative-led government, favored privatization rather than government expansion, led the country through the Falklands War with Argentina, and did it all with a stern no-nonsense flair that earned her the nickname "The Iron Lady." Although Thatcher was elected to three consecutive terms, political disputes and discontent within her party forced her to resign on 28 November 1990. She was succeeded by fellow Conservative John Major. She published the memoirs The Downing Street Years (1993) and The Path to Power (1995).