أحمد بن زين الدين الأحسائي
In the early 19th century, the Shaykhi school of Twelver Shi'ism emerged in Iran when some Twelvers considered Shaykh Ahmad al-Ahsa'i and his successor Kazim Rashti as the to the Hidden Imam. This tradition provided the foundation of the religion of Bábism, when its eponymous founder, Ali Muhammad Shirazi, took the title of Báb.