Ismail as-Sadr (Arabic: اسماعيل الصدر‎) (died 1919-1920) was a Lebanese Grand Ayatollah (literally "sign of Allah"), a title which is used in Iran and Iraq referring to a Twelver Shi'a scholar who is a fully qualified mujtahid who asserts authority over peers and followers by virtue of sufficient study and achievement of the level of necessary competencey needed to obtain permission (ijāza) to practice ijtihad.