What is a single word for a ruling representative of a supreme leader who carries out his orders?

What is a single word for a ruling representative of a supreme leader who carries out his orders and at the same time has almost complete rule over the portion of the earth in which the supreme leader has placed him?

Solution 1:

The word used in colonial times was Viceroy.

Nowadays, we use the term Vice-President. But "viceroy" means "vice-king." (Roi is French for king).

Solution 2:

There are several other possibles, but I like plenipotentiary (if you're describing) and The Great Panjandrum (if you're lampooning) best. Whats the context?

Solution 3:

There may be a better position of authority title, but would "proxy" be appropriate?

Solution 4:

Move a little bit east and one might encounter the grand vizier.

Solution 5:

How about regent?

a person who governs a kingdom in the minority, absence, or disability of the sovereign; a person who rules or reigns