Iranian state television announced on Sunday that Supreme Leader Ali Khamenei was killed.
The broadcaster did not immediately provide further details about the circumstances of his death.
State media also reported that 40 days of public mourning was declared in Iran following the announcement.
The Supreme National Security Council said Supreme Leader Khamenei was killed at his office on Saturday morning and that his death would mark the beginning of a "great uprising against the tyrants of the world."
Earlier on Saturday, US President Donald Trump said in a post on his social media platform Truth Social that Khamenei was "dead."
"Khamenei, one of the most evil people in History, is dead," Trump wrote.
