Abū ʿAlī Ardistānī, known as Dihdār, a well-known Ismaili preacher and dāʿī (summoner) to the Ismaili creed of the 5th/11th century, and a close companion of Ḥasan-i Ṣabbāḥ.

He was born in Zawāra, a dependency of Ardistān, where he grew up and later on embraced Ḥasan-i Ṣabbāḥ's teachings. When in 483/1090 Ḥasan-i Ṣabbāḥ turned the castle of Alamūt into his headquarters, he made Abū ʿAlī a dāʿī and appointed him chief Ismaili missionary for the Qazwīn and Ṭāliqān region. As a result of his fear of the growing power of the Ismailis, together with Ḥasan-i Ṣabbāḥ'…