Abū al-Fath Abd al-Rahman Mansūr al-Khāzini or simply al-Khāzini was an Iranian astronomer, mechanician and physicist of Byzantine Greek origin who lived during the Seljuk Empire. His astronomical tables, written under the patronage of Sultan Sanjar, are considered to be one of the major works in mathematical astronomy of the medieval period. He is considered to have been one of the greatest scientists of his era, among the greatest makers of scientific instruments of any time, and as "the physicist of all physicists".