Shaykh Tusi (Persian: شیخ طوسی), full name Abu Ja'far Muhammad ibn al-Hasan al-Tusi (Arabic: ابو جعفر محمد بن الحسن الطوسي, romanized: Abū Jaʿfar Muḥammad ibn al-Ḥasan al-Ṭūsī), known as Shaykh al-Ta'ifah (Arabic: شيخ الطائفة, romanized: Shaykh al-Ṭāʾifah) was a prominent Persian scholar of the Twelver school of Shia Islam. He was known as the "sheikh of the sect (shaikh al-ta'ifah)", author of two of the four main Shi'i books of hadith, Tahdhib al-Ahkam and al-Istibsar, and is believed to have founded the hawza. He is also the founder of Shia jurisprudence. Source: Wikipedia (en)