Abu Ali al-Hasan al-Tusi Nizam al-Mulk (April 10, 1018 – October 14, 1092), better known as Khwaja Nizam al-Mulk Tusi (Persian: Khwāğa Nizāmu l'Mulk al-Ṭusī) is a Persian scholar and vizier of the Seljuq Empire.

He holds near absolute power for 20 years after the assassination of Alp Arslan in 1072.

"Nizam al-Mulk" is an honorific that he assumes after achieving prominence.

It means in Arabic: "good order of the kingdom."