Aga Khan IV

Shah Karim al-Hussaini (13 December 1936 – 4 February 2025), known simply as Aga Khan IV, was the 49th imam of Nizari Isma'ilism from 1957 until his death in 2025. He inherited the Nizari imamate and the title of Aga Khan at the age of 20 upon the death of his grandfather, the Aga Khan III. During his imamate, he was also known by the religious title Mawlānā Hazar Imam by his Isma'ili followers.

Al-Husseini's net worth was estimated at over US$13.3 billion by Vanity Fair in 2013. Forbes included al-Husseini in its list of the world's fifteen richest royals, though he held no political sovereignty or territorial authority. The designation referred to his hereditary role as Imam of the Nizari Ismailis, not to any formal royal or monarchical status. He was the founder and chairman of the Aga Khan Development Network, one of the largest private development networks in the world.

Karim al-Husseini was born in Geneva, Switzerland, on 13 December 1936, the eldest son of Aly Khan (1911–1960) and his first wife, Taj-ud-dawlah Aga Khan (formerly Joan Yarde-Buller, 1908–1997). His mother was the eldest daughter of the British peer John Yarde-Buller, 3rd Baron Churston.

He was declared healthy despite being born prematurely. His brother, Amyn Aga Khan, was born a year later in 1937. In 1949, his parents divorced in part due to his father's extramarital affairs, and shortly after, his father married American actress Rita Hayworth—with whom he had a daughter, Yasmin Aga Khan, the half-sister of al-Husseini.

He also had a half-brother, Patrick Benjamin Guinness (1931–1965), from his mother's first marriage, as Joan Yarde-Buller was previously married to Loel Guinness of the banking Guinnesses.

Karim spent the years during World War II in Nairobi, Kenya, where his early education was through private tutoring. He later attended the Institut Le Rosey in Switzerland for nine years where he achieved, in his words, "fair grades". He was admitted to the Massachusetts Institute of Technology where he wanted to study science, but his grandfather, Aga Khan III, vetoed the decision. Instead he attended Harvard University, where he was elected a member of The Delphic Club and majored in Islamic history.

When his grandfather died, he was thrust into the position of the Aga Khan. At the time of his accession to the Imamate in 1957, Karim was a university student. Reflecting on the transition, he later stated that he had to set aside plans for further academic study in order to assume his new responsibilities as Imam. He graduated from Harvard University in 1959, two years after ascending the imamate, with a Bachelor of Arts degree in history (with Cum Laude honours) and his varsity H for the Harvard Crimson men's soccer team.

He was a competitive downhill skier, representing Great Britain at the FIS Alpine World Ski Championships 1962 and then Iran in the 1964 Winter Olympics.