Qutb ad-Dīn Haydar is a Persian Sufi saint, who died about 1221 CE/618 AH. Haydar - the Persian form of his name is Heydar - founded an order of mendicant dervishes known as the Haydariyya known for their celibacy and self-mortification through piercing their own bodies with iron rings. He is also known by Heyder.
