Secretary-General of the United Nations
Head of Earth's world government in The Expanse: directly elected, commander-in-chief of humanity's largest military, and arguably the most powerful person alive from Leviathan Wakes onward.
The Secretary-General of the United Nations is the most powerful office a human being can hold in the Solar System. The UN is no advisory body: it is Earth's world government, and the Secretary-General heads it, directly elected by the citizens of a planet of thirty billion and serving as commander-in-chief of the largest navy and army humanity has ever fielded. The office sits at one pole of the founding rivalry, opposite the government of an independent Mars, with the Belt's scattered millions subject to decisions made in both capitals and represented in neither. Individual holders of the office come and go; the weight of the chair itself is a constant of politics.
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