Sheikh Safi-ad-din Is'haq Ardabili (of Ardabil) (1252–1334) (Persian: شیخ صفیالدین اردبیلی), was the Kurdish eponym of the Safavid dynasty, and the spiritual heir and son in law of the great Sufi Murshid (Grand Master) Sheikh Zahed Gilani, of Lahijan in Gilan province in northern Iran. Most of what we know about him comes from the Safvat as-safa, a hagiography written by one of his followers.
Sheikh Safi al-Din's has composed poems in the Iranian dialect of old Tati. He was a seventh-generation descendant of Firuz Shah Zarrin Kolah, a local Iranian dignitary.
Sheikh Safi al-Din inherited Sheikh Zahed Gilani's Sufi order, the "Zahediyeh", which he later transformed into his own, the "Safaviyya". Sheikh Zahed Gilani also gave his daughter Bibi Fatemeh in wedlock to his favorite disciple. Sheikh Safi al-Din, in turn, gave a daughter from a previous marriage in wedlock to Shaikh Zahed Gilani's second-born son. Over the following 170 years, the Safaviyya Order gained political and military power, finally culminating in the foundation of the Safavid dynasty.