Ṣadr ad-Dīn Muḥammad Shīrāzī, more commonly known as Mullā Ṣadrā (Persian: ملا صدرا; Arabic: صدر المتألهین; c. 1571/2 – c. 1635/40 CE / 980 – 1050 AH), was an Iranian Twelver Shi'i Islamic mystic, philosopher, theologian, and ‘Ālim who led the cultural renaissance in the country during the 17th century. According to Oliver Leaman, Mulla Sadra is arguably the single most important and influential philosopher in the Muslim world in the last four hundred years. Though not its founder, he is considered the master of the Illuminationist (or, Ishraghi or Ishraqi) school of Philosophy, a seminal figure who synthesized the many tracts of the Islamic Golden Age philosophies into what he called the Transcendent Theosophy or al-hikmah al-muta’āliyah.
Mulla Sadra brought "a new philosophical insight in dealing with the nature of reality" and created "a major transition from essentialism to existentialism" in Islamic philosophy, although his existentialism should not be too readily compared to Western existentialism. His was a question of existentialist cosmology as it pertained to God, and thus differs considerably from the individual, moral, and/or social, questions at the heart of Russian, French, German, or American Existentialism.