Rezā Shāh, also known as Rezā Shāh Kabir (Reza Shah the Great), or Rezā Shāh Pahlavi (Persian: رضا شاه پهلوی, pronounced ), (March 16, 1878 – July 26, 1944), was the Shah of the Imperial State of Iran from December 15, 1925 until he was forced to abdicate by the Anglo-Soviet invasion of Iran in September 16, 1941.

In 1925, Reza Shah overthrew Ahmad Shah Qajar, the last Shah of the Qajar dynasty, and founded the Pahlavi Dynasty. He established an authoritarian government that valued nationalism, militarism, secularism and anti-communism combined with strict censorship and state propaganda. Known as quite intelligent despite his lack of formal education, Reza Shah introduced many socio-economic reforms, reorganizing the army, government administration, and finances. To his supporters his reign brought "law and order, discipline, central authority, and modern amenities - schools, trains, buses, radios, cinemas, and telephones". However, his attempts of modernisation have been criticised for being "too fast" and "superficial", and his reign a time of "oppression, corruption, taxation, lack of authenticity" with "security typical of police states." . Although for many Iranian nationalists he is considered the father of modern Iran.