Ayatollah Ahmad Jannati Massah (Persian: احمد جنتی, date of birth: 1927) is a hardline Iranian politician, fundamentalist Shi'i cleric and a founding member of Haghani school with close ties with Mahmoud Ahmadinejad and Mesbah Yazdi. He is the conservative chairman of the Guardian Council, the body in charge of checking legislation approved by Majlis with the Constitution and sharia, and approving the candidates in various elections. He is also a temporary Friday prayer imam of Tehran. His son Hussein Jannati was a member of People's Mujahedin of Iran and was killed in a street battle by the Islamic Republic security forces in 1981.
He has been a member of the Guardian Council since 1980 and has been its chair since 1988. Ahmad Jannati wields considerable influence because he simultaneously holds seats in the Guardian Council, Expediency Discernment Council, and Assembly of Experts.
Jannati was one of the founders of Haghani School, one of the most influential religious schools in Iran, and has had an influence on President Mahmoud Ahmadinejad.