Hassan ibne Sabbah (circa 1050–1124) was the leader of the Nizari Ismailites and the founder of the order known as Assassins.Assassins, who are often referred to as the Hashshashin, was a group of fedayeen.br br Hassan ibne Sabbah was a missionary who converted the Nizari in the late 11th century in the heart of the Alborz Mountains of northern Persia. He later seized a mountain fortress called Alamut.br image resources,br unknown - ? ????? ???? - copied from ? CC BY-SA 3.