Hasan ibn Zayd, Tabaristan ruler
Al-Ḥasan ibn Zayd ibn Muḥammad ibn Ismā‘il ibn al-Ḥasan ibn Zayd (Arabic: الحسن بن زيد بن محمد; died 6 January 884), also known as al-Da‘ī al-kabīr (Arabic: داعي الكبير, "the Great/Elder Missionary"), was an Alid who became the founder of the Zaydid dynasty of Tabaristan.