Hülegü Khan

Hülegü Khan (c. 1217 – 8 February 1265) was a Mongol ruler who conquered much of Southwest Asia. He was the grandson of Genghis Khan and a brother of Kublai Khan.

In 1256, Mongol forces under Hülegü's command attacked various Assassin fortresses along the Levant, in vengeance of Genghis Khan's murder at the hands of the Syrian Assassin Darim Ibn-La'Ahad and the Mongolian Assassin Qulan Gal.

Source

 * Assassin's Creed Encyclopedia