Abu Mansur Fulad Sutun (died 1062) was the Buyid amir of Fars, ruling more or less continuously from 1048 until his death. He was the son of Abu Kalijar.
After the death of Abu Kalijar in 1048, his eldest son Abu Nasr Khusrau Firuz had succeeded him as senior amir in Baghdad and assumed the title "al-Malik al-Rahim." Abu Mansur, however, rose up against his brother and control of Fars. Al-Malik al-Rahim invaded Fars and occupied Shiraz, but turmoil between the Turks and Daylamites in his army forced him to abandon the province and leave it in the hands of Abu Mansur.
In 1051 or 1052 al-Malik al-Rahim's army again invaded Fars and this time defeated Abu Mansur and his allies. Fars was for the next year or so reunited with Iraq and governed by a third son of Abu Kalijar, Abu Sa'd, on al-Malik al-Rahim's behalf. Abu Mansur, however, requested the support of the Seljuk sultan Toghrul Beg, and was able to recapture Shiraz in 1053 or 1054. He then recognized Toghrul Beg as his overlord and placed the sultan's name first in the khutba, in front of al-Malik al-Rahim's.
In December 1055 al-Malik al-Rahim was arrested and deposed by Toghrul Beg's forces in Baghdad, bringing an end to Buyid rule in Iraq. Abu Mansur, on the other hand, was able to remain in power in Fars for another seven years as a Seljuk vassal. Constant fighting with his brothers, however, weakened his rule, and in 1062 he was killed while fighting against the Kurdish Shabankara tribal chief Fadluya. The Seljuks shortly afterward entered Shiraz and took control of Fars.