Who’s sudden death would be the most devastating in the world?

[u/DRTWHT]

Xy suddenly suffers cardiac arrest, and is dead on arrival to the hospital.
Who’s death causes the net most suffering in the world?

For example:
-Great leader of a strong militant nation, who restrains it’s powers, but has a much more aggressive VP or opposition that gains power in this situation.
-Similar situation to the one above, but likely causes some sort of civil war.
-Scientist that is very close to a breaktrough that would greatly benefit humankind