Prince Karim Husseini Aga Khan IV inherits the office of Imamat as the 49th Imam of Shia Imami Ismai'li worldwide, after the death of Sir Sultan Mahommed Shah Aga Khan III.

Prince Karim al-Husseini, known as the 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.

Ismailism is a branch of Shia Islam. The Isma'ili get their name from their acceptance of Imam Isma'il ibn Jafar as the appointed spiritual successor (imām) to Ja'far al-Sadiq, wherein they differ from the Twelver Shia, who accept Musa al-Kazim, the younger brother of Isma'il, as the true Imām.

Sir Sultan Muhammad Shah, known as Aga Khan III, was the 48th imam of the Nizari Ism'aili branch of Shia Islam. He was one of the founders and the first permanent president of the All-India Muslim League (AIML). He was also a descendant of al-Mu'izz li-Din Allah (932-975).