Ismailis (Sevener Shi'ites)
The Ismaili faith is headed by Agha Khan. They believe he's just the latest in an unbroken line of leaders, spanning over a millennium. He is an active figure in international humanitarian efforts.
The Fatimids, an Ismaili dynasty, ruled as Caliphs in Egypt from 969 to 1171. Under the Fatimids, Egypt became the center of a vast empire, which at its peak comprised North Africa, Sicily, Palestine, Syria, the Red Sea coast of Africa, Yemen, and the Hijaz in Arabia, including the holy cities of Mecca and Medina. Control of the holy cities conferred enormous prestige on a Muslim ruler and the power to use the yearly pilgrimage to Mecca to his advantage. After the empire fell, for the most part Ismaili presence in the Muslim world greatly diminished, except for an Ismaili sub-sect, the Assassins (Nizaris), who were quite powerful for over a century after that.
Numbering at 15 million adherents, the Ismailis are the second largest Shi'ite group and found mostly in the Indian subcontinent, Syria, Saudi Arabia, Yemen and East Africa. Except for a few sub-sects, most hold Aga Khan as a direct descendent of Mohammed in the Imami line. He has become international celebrity championing human rights.