The individual known as the "Iron Lady" during her time as British Prime Minister is Margaret Thatcher. Serving from 1979 to 1990, she became the first woman to lead the United Kingdom. Thatcher was known for her strong conservative policies, advocating for free markets, reducing government intervention, and promoting individual accountability. Her nickname stemmed from her uncompromising stance against the Soviet Union and her firm leadership style. Thatcher's policies significantly transformed Britain's economy, leading to both praise and criticism, establishing her as a divisive yet influential figure in global politics.