Abū al-Fath Abd al-Rahman Mansūr al-Khāzini or simply al-Khāzini (أبوالفتح عبدالرحمن منصور الخازنی (Persian), flourished 1115–1130) was an Iranian astronomer, during the Seljuk Empire. His astronomical tables written under the patronage of Sultan Sanjar (Zīj al-Sanjarī, 1115) is considered to be one of the major works in mathematical astronomy of the medieval period. He provided the positions of fixed stars, and for oblique ascensions and time-equations for the latitude of Marv in which he was based. He also wrote extensively on various calendrical systems and on the various manipulations of the calendars. He was the author of an encyclopedia on scales and water-balances.