The office of Prime Minister of Iran was established in 1907 during the Persian Constitutional Revolution, and existed until 1989 when the office was abolished after a constitutional referendum.
The prime minister was the head of government of Iran.
Ali Asghar Khan was the first and Mir-Hossein Mousavi was the last prime minister of Iran.
Before the Constitutional Revolution, the head of government was called Grand Vizier (Sadr-e A'zam or Vazir-e A'zam).