Rahim Al-Hussaini was named Wednesday as the new Aga Khan, spiritual leader of the world’s millions of Ismaili Muslims, following the death of his father.

LISBON, Portugal — The Aga Khan, who became the spiritual leader of the world’s millions of Ismaili Muslims at age 20 as a Harvard undergraduate and poured a material empire built on billions of dollars in tithes into building homes, hospitals and schools in developing countries, has died. He was 88.