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.

The Aga Khan IV, the spiritual leader of the world’s Shi’ite Ismaili Muslims, has died at the age of 88. The wealthy imam, who promoted a moderate form of Islam, has also been known for his multimillion-dollar development projects that have benefited communities throughout Asia and Africa.