Who was the most recent Shah of Iran?
Mohammad Reza Pahlavi
Mohammad Reza Pahlavi (Persian: محمدرضا پهلوی‎, pronounced[mohæmˈmæd reˈzɒː ˈʃɒːh pæhlæˈviː]; 26 October 1919– 27 July 1980),[3] also known as Mohammad Reza Shah, was the last Shah of Iran from 16 September 1941 until his overthrow by the Iranian Revolution on 11 February 1979. Mohammad Reza Shah took the title Shahanshah ("King of Kings")[4] on 26 October 1967. He was the second and last monarch of the House of Pahlavi. Mohammad Reza Shah Pahlavi held several other titles, including that of Aryamehr ("Light of the Aryans") and Bozorg Arteshtaran ("Commander-in-Chief"). His dream of what he referred to as a "Great Civilisation" (Persian: تمدن بزرگ‎, romanized:tamadon-e bozorg) in Iran led to a rapid industrial and military modernisation, as well as economic and social reforms.[5]
Background and causes of the Iranian Revolution
Its causes – why the last Shah of Iran (Mohammad Reza Pahlavi) was overthrown and why he was replaced by an Islamic Republic – are the subject of historical debate. The revolution was in part a conservative backlash against the westernization, modernization and secularization efforts of the Western-backed Shah, and a more popular reaction to social injustice and other shortcomings of the "ancien régime". 
The Shah was perceived by common Iranian people as a puppet of the United States. Under the Shah's rule, Western powers exploited Iran's natural resources blatantly. Toward the people, The Shah's regime was oppressive, brutal, and corrupt; it also suffered from basic functional failures, like overly ambitious economic programs that brought economic bottlenecks, shortages and inflation.