Prince Shah Karim al-Hussaini (13 December 1936 – 4 February 2025), known simply as Aga Khan IV, was the 49th Imam of Nizari Isma'ili Shia Islam 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, Sultan Muhammad Shah (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, a private development network.
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.
Succession and appointment as Imam
After the death of Aga Khan III in 1957, Shah Karim al-Husseini was appointed as the 49th Imam of the Nizari Ismaili community at the age of 20. His designation was made through the will of his grandfather, bypassing his father, Aly Khan, and his uncle, Sadruddin Aga Khan. This was the second recorded instance in Nizari Ismaili history where a grandson, rather than a son, was named as Imam.
The will cited "fundamentally altered conditions in the world" as part of the rationale for selecting a younger successor:"In view of the fundamentally altered conditions in the world [which] has provoked many changes, including the discoveries of atomic science, I am convinced that it is in the best interests of the Nizari Ismaili community that I should be succeeded by a young man who has been brought up and developed during recent years and in the midst of the new age, and who brings a new outlook on life to his office."This statement was later used by some within the community to frame al-Husseini as an "Imam of the Atomic Age," a phrase that has appeared in various publications but has no official doctrinal status. The will also recommended that the new Imam, during his early years in the role, consult his grandmother, Om Habibeh Aga Khan, on general matters.
Karim al-Husseini became the 49th hereditary Imam of the Nizari Ismaili Muslims in 1957 following the death of his grandfather. Installation ceremonies were conducted at multiple locations between 1957 and 1958, during which he spoke about issues such as interethnic and interfaith relations.
In 1972, the government of Uganda, led by President Idi Amin, expelled people of South Asian origin, including many Nizari Ismailis, giving them 90 days to leave the country. Following this, Karim al-Husseini contacted Canadian Prime Minister Pierre Trudeau, which resulted in Canada accepting a significant number of displaced Ismailis. He also coordinated efforts to assist Ismailis displaced from Tanzania, Kenya, and Myanmar with resettlement in other countries, primarily in Asia, Europe, and North America. Most of the initial resettlement problems were overcome rapidly by Nizari Ismailis due to their educational backgrounds and high rates of literacy, as well as the efforts of the host countries, along with support from Nizari Ismaili community programmes.
Al-Husseini encouraged members of the Nizari Ismaili community in industrialised countries to support development initiatives in regions with significant Ismaili populations. Karim al-Husseini described the role of the Imam as involving both religious interpretation and attention to the social welfare of the community. He has emphasized the importance of engagement between Ismaili communities and the broader societies in which they live.
He was among the Shia signatories of the 2004 Amman Message, which addressed the inclusion of various denominations of Islam within the Muslim community.
During the 2006 controversy surrounding Pope Benedict XVI's lecture, Karim al-Husseini expressed concern over deteriorating interreligious relations and suggested the situation presented an opportunity for dialogue about religion and reason
When he was asked about his view on the consumption of alcohol in a 1965 interview with The Sunday Times, al-Husseini said, in line with Muslim teaching:
Our belief is that the thing which separates man from the animals is his power of thought. Anything that impedes this process is wrong. Therefore, alcohol is forbidden. I have never touched alcohol. But this, to me, is not a puritan prohibition. I don't want to drink. I've never wanted to drink. There's no pressure being placed on me by my religion.