Hakīm Sa'd-al-Dīn ibn Shams-al-Dīn Nizārī Bīrjandī Quhistānī (), or simply Nizari Ghohestani (died 1320 CE), was a 13th-century Nizari Ismaili author and poet, who lived in the time of the Imam Shams al-Din (Nizari) Muhammad. Nizari was born into a family of landed gentry approximately a decade after the capitulation of the Alamut state and hailed from the town of Birjand. Nizari is the only Ismaili poet of this period whose works are extant. Nizari Quhistani’s work was quoted by many later Ismaili authors, such as the Persian Khwāja Muḥammad Riḍā b. Sulṭān Ḥusayn, also known as Khayrkhvah-i Harati. Life Nizari completed his primary education in Birjand and Qa’in, and became adept in Arabic and Persian literature and philosophy. He received higher education at a college (madrasa), which he deplored as it was quite unlike the education he had received in his home town. For a time, he served as one of the only Ismaili officials at the court of Malik Shams-uddin Muhammad Kurt I (d. 1285 CE) better known as Shams al-Din Kart in Herat. To serve the court was both a precious and precarious position for Nizari. In this role, Nizari toured Khurasan, Rayy, Sistan and Quhistan, eventually meeting the successor of the Imam Rukn al-Din Khwurshah, whom he identified as the Shah Shams. However, when an intimate of his was sentenced to death, Nizari could not hold his silence and after speaking out against the court, was discharged from his position. Nizari died in 1320 CE, approximately ten years after the death of the Imam Shams al-Din Muhammad. Nizari Quhistani's pen name “Nizari” has been a topic of debate amongst scholars. Some historians including Mirkhwand, Khwandamir and Dawlatshah have suggested that the moniker implies Nizari's adherence to the Ismaili Imam Nizar. A second theory for Nizari's nom de plume is that he was of a slim (nizār) build, though this has been dismissed by the prominent scholar of Persian history E. G. Browne. However, even the theory of Nizari's allegiance to an Imam Nizar raises questions about the identity of such a figure. It is therefore unclear whether the name denotes Nizari's allegiance to the first Imam Nizar, that is Nizar b. al-Mustansirbillah, denoting him as a partisan of the Nizari branch of the Ismaili faith, or to the successor of the Imam Shams al-Din Muhammad who was known both as Imam Nizar and Imam Qasimshah. Shafique