Ali al-Husayni al-Sistani is an Iranian-Iraqi Islamic scholar. One of the most senior scholars of Twelver Shia with the rank of Grand Ayatollah and marja', he has been described as the spiritual leader of Shia Muslims worldwide, "the undisputed leader of Iraq's Shias", included in top positions of "The Muslim 500: The World's Most Influential Muslims", from 2009 to 2023, and named one of the 100 most influential people in the world by Time magazine in 2004 and 2005.

Grand Ayatollah Sayyid Hossein Ali Tabatabaei Borujerdi was a leading Iranian Shia Marja' in Iran from approximately 1947 to his death in 1961.