Mīrzā Ismāʿīl Khān Amīn al-Mulk (1867-99) was the younger brother of the Iranian prime minister ( ṣadr-i aʿẓam ) Mīrzā ʿAlī Aṣghar Khān Amīn al-Sulṭān (Atābak-i Aʿẓam, d. 1907), under whom he served in several important offices, most notably as minister of the treasury ( khizāna ), during the last decade of the reign of Nāṣir al-Dīn Shāh Qājār (r. 1848-96; Bāmdād, 1:127-9; Amanat, Amīn-al-Solṭān; and Amanat, Atābak-e Aʿẓam). The brothers' father, Āqā (Muḥammad) Ibrāhīm Khān Arbāb (Amīn al-Sulṭān, d. 1883),