Abu Ali Hasan ibn Ali Tusi (April 10; 1018 - October 14; 1092); better known by his honorific title of Nizam al-Mulk (Persian: 'Order of the Realm') was a Persian scholar and vizier of the Seljuq Empire. He held near absolute power for 20 years after the assassination of Alp Arslan in 1072.

Nizam al-Mulk was in turn assassinated en route from Isfahan to Baghdad on 14 October 1092. It is recorded that he was stabbed by the dagger of a member of the Assassins (Hashshashin) sent by the notorious Hassan-i-Sabbah near Nahavand; as he was being carried on his litter. The killer approached him disguised as a dervish. Pictures From History