أحمد بن زين الدين الأحسائي
Shaykh Ahmad bin Zayn al-Dín bin Ibráhím al-Ahsá'í () (1753–1826), commonly known as Shaykh Ahmad or al-Ahsá'í, was a prominent 19th-century Shia Muslim theologian and jurist, founded the influential Shaykhí school of Twelver Shiism, which attracted followers from throughout the Persian and Ottoman Empires.