Grand Ayatollah Mohammad Mohammad Sadeq al-Sadr (Arabic: محمد محمّد صادق الصدر; Muḥammad Muḥammad Ṣādiq aṣ-Ṣadr) (March 23 1943 – February 19, 1999), often referred to as Muhammad Sadiq as-Sadr which is his father's name, was a prominent, Iraqi Shi'a cleric of the rank of Grand Ayatollah. He called for government reform and the release of detained Shi'a leaders. The growth of his popularity, often referred to as the followers of the Vocal Hawza, also put him in competition with other Shi'a leaders, including Ayatollah Mohammed Baqir al-Hakim who was exiled in Iran.

He was killed in the Iraqi city of Najaf along with two of his sons as they drove through the town. Their car was ambushed by men, and both his sons were killed by gunfire while he was severely injured. He died an hour later in the hospital. Shi'as in Iraq, as well as most international observers, hold that the Iraqi Baathist government was implicated if not directly responsible. Following the fall of Baghdad, the majority-Shi'a suburb of Saddam City was unofficially but popularly renamed to Sadr City in his honor. His son, Muqtada al-Sadr, bases his legitimacy upon his relationship to his father, and gains much of his support through the popularity of his father.

He was a student of his father's cousin Grand Ayatollah Muhammad Baqir al-Sadr, the father-in-law of Muqtada al-Sadr.