Mohsen Fakhrizadeh was one of Iran's foremost nuclear scientists.
A professor of physics and an officer in the Iranian Revolutionary Guard, he was a well-known figure among the intelligence communities of Iran's foes, chiefly the United States and Israel.
Israeli Prime Minister Benjamin Netanyahu has named him directly when talking about the threat Iran posed as an aspiring nuclear power.
"Remember that name," he said in a 2018 news conference.
In January, the United States assassinated the top Iranian general Qassem Soleimani.
In a sense, this is the nuclear equivalent of the January assassination.
In taking out Qassem Soleimani, the Americans sought to stem or at least slow down Iran's malign involvement across an arc of the Middle East - an Iranian influence spearheaded by him.
The obvious motive behind the assassination of Mohsen Fakhrizadeh would be to slow down Iran's nuclear proliferation program. Or at least that would be the hope.
There is an acutely political element to all of this too. Both Israel and the United States, under the Trump administration, have repeatedly warned of the growing threat that they see from Iran.
Trump ditched Obama's nuclear deal but has been unable to replace it with anything. The Trump-Netanyahu concern is that a Biden administration will try and resurrect the deal.
By assassinating a top nuclear scientist they make it harder for a Biden administration to rekindle the deal and at the same time they remove one peg in the Iranian quest for a nuclear weapon.
A week ago, President Trump asked for military options for attacking Iran - to hit a nuclear site.
He chose not to act in the end. But there has been an expectation that his administration and Israel would use these last few months to hit Iran in one way or another and slow its nuclear ambitions.
Their calculation is that Iran would not respond before he leaves office.
At this stage, of course, there has been no claim of responsibility and they may never be.
Israel is widely believed to have been behind a series of assassinations on Iranian nuclear scientists a decade ago but it has never admitted it.
The Iranians have vowed to avenge whoever was responsible for this assassination.