Sayyid Ali Hosseini Khamenei served as Iran’s supreme leader and was the country’s most powerful political figure, holding ultimate authority over foreign policy, the Islamic Revolutionary Guard Corps (IRGC) and major domestic institutions. Born into a clerical family in Mashhad, he rose through the ranks during the 1979 Islamic Revolution as a religious student and close adviser to Ayatollah Ruhollah Khomeini. After the revolution Khamenei held several senior posts, including defense minister and later president, and when Khomeini died he was chosen by the assembly of senior clerics to succeed him as supreme leader.
Khamenei’s outlook was shaped by historical grievances—most notably the 1950s U.S.-backed overthrow of Iran’s government—and by revolutionary events such as the 1979 revolution and the 1980 hostage crisis, which fostered a persistent distrust of the United States. He framed his rule around protecting the Islamic Republic from internal dissent and external threats, particularly from the U.S. and Israel, and he criticized initiatives he saw as compromising revolutionary principles, including expressing skepticism about the 2015 international nuclear agreement.
As supreme leader, Khamenei exercised oversight of the IRGC and intelligence services and played a decisive role in the selection and policy direction of Iran’s presidents and other senior officials. Even after health issues—he underwent prostate surgery in 2014—he remained central to policymaking. His tenure was marked by harsh crackdowns on dissent and sustained efforts to preserve the theocratic system amid mounting social and economic pressures. In later years mass protests posed unprecedented challenges to the regime’s legitimacy and, for the first time in decades, focused direct criticism on the supreme leader himself, yet Khamenei stood as a steadfast defender of the Islamic Republic’s core principles.
Succession under the constitution and in crisis
Iran’s constitution assigns the Assembly of Experts—a body of roughly 88 clerics—the responsibility of selecting a new supreme leader. Immediately after a leader’s death the constitution provides for a provisional arrangement in which power is exercised collectively by the president, a leading cleric and a senior figure from the judiciary or armed forces until the Assembly convenes to choose a successor.
In practice, succession is influenced by factional balances, the cohesion of the IRGC and the resilience of state institutions. Analysts note that strikes or assassinations targeting senior leaders and security commanders can create fragmentation and uncertainty. Recent dynamics in which senior IRGC and defense figures have been killed in attacks underscore how leadership churn can complicate the regime’s ability to respond and maintain centralized control.
What comes next
If a supreme leader is killed or incapacitated, Iran’s short-term stability will depend on whether the Revolutionary Guards, the military and the clerical establishment remain unified. If they do, the system is likely to produce another leader from within the clerical ranks or the revolutionary establishment, preserving continuity rather than prompting rapid political liberalization. If significant fissures open among security commanders, clerics and politicians—especially following targeted strikes—succession could become contested with potentially destabilizing consequences.
Throughout his decades in power, Khamenei’s overriding priority was the survival of the Islamic Republic. His death or removal would be a profound turning point; who succeeds him and how the Iranian power structure reacts will shape the country’s domestic trajectory and regional behavior in the months and years that follow.