Mohammed Reza Shah Pahlavi was the last Shah of Iran, ruling from 1941 until 1979. He was a controversial figure, known for his efforts to modernize Iran and his close ties to the West, particularly the United States. His rule was marked by economic development and social reforms, but also by political repression and human rights abuses. Pahlavi's close relationship with the United States ultimately led to his downfall, as widespread discontent with his regime culminated in the Iranian Revolution of 1979, which resulted in his overthrow and the establishment of an Islamic republic in Iran.