'King of Kings' in the Bible

Artaxerxes, king of kings, to Ezra the priest, scribe of the law of the God of heaven, all peace;

For this is what the Lord has said: See, I will send up from the north Nebuchadrezzar, king of Babylon, king of kings, against Tyre, with horses and war-carriages and with an army and great numbers of people.

You, O King, king of kings, to whom the God of heaven has given the kingdom, the power, and the strength, and the glory,

Which at the right time he will make clear, who is the eternal and only Ruler, King of kings, and Lord of lords;

These will make war against the Lamb, and the Lamb will overcome them, because he is the Lord of lords and King of kings; and those who are with him are named, marked out, and true.

And on his robe and on his leg is a name, KING OF KINGS, AND LORD OF LORDS.