The killing of General Qassem Soleimani, who led the elite Quds Force in Iran’s Islamic Revolutionary Guard Corps (IRGC), was ordered by US President Donald Trump.
A US air raid hit his convoy near Baghdad International Airport on Friday.
The assassination marks a dangerous escalation in US-Iran tensions.
Iran’s Supreme Leader Ayatollah Ali Khamenei warned there would be “harsh revenge”.
A senior Iraqi official also died in the attack, and all Americans have now been advised to leave Iraq because of the threat of reprisal attacks.