Nizari Ismailis affirm that a living, present Imam, descended from the Prophet through Ali and Fatima, continues in every age to guide the community, interpret the faith for its time, and hold spiritual authority. Unlike Twelver Shia, who hold that their twelfth Imam entered concealment, the Nizari line has remained manifest, its present holder bearing the title Aga Khan. The Imam is regarded not as a lawgiver above the Prophet but as the authoritative interpreter who keeps the tradition living rather than fixed.
The office passed most recently on 4 February 2025, when Aga Khan IV (Prince Karim al-Husayni), who had held the imamate since 1957, died in Lisbon at 88; his son, Prince Rahim al-Husayni, was named Aga Khan V and installed as the fiftieth hereditary Imam within days, on 11 February 2025, continuing a line the community traces to Ali through the Fatimid caliphs. Succession is not automatic by strict primogeniture: Aga Khan III, who led the community from 1885 to 1957, notably passed over his own son, Aly Khan, and named his twenty-year-old grandson Karim as successor in his will, citing the need for a leader attuned to a rapidly changing modern world, a precedent underscoring that the Imam himself designates his successor rather than descent by seniority alone determining it.