The influential figure in history known as the "Iron Lady" is Margaret Thatcher. As the first female Prime Minister of the United Kingdom, she served from 1979 to 1990 and was known for her strong, uncompromising leadership style. Thatcher implemented significant economic policies that emphasized free markets, deregulation, and privatization, earning both staunch supporters and fierce critics. Her legacy is marked by her impact on British and global politics, as well as her role in shaping the conservative movement in the late 20th century.