Nizam al-Mulk
The first notable assassination was that of powerful Seljuk vizier Nizam al-Mulk in 1092 who had helped propel Barkiyaruq to lead the sultanate. Sabbah is reputed to have remarked "the killing of this devil is the beginning of bliss" on hearing to the death of Nizam. Of the 50 assassinations conducted during Sabbah's reign, more than half were Seljuk officials, many of whom supported Muhammad I Tapar. The story (presented here) claiming a friendship among Nizam al-Mulk, Hassan-i Sabbah and Omar Khayyam described by Edward FitzGerald in his translation of "The Rubaiyat of Omar Khayyam" is most certainly false.