New Revised Standard Version
They have as king over them the angel of the bottomless pit; his name in Hebrew is Abaddon, and in Greek he is called Apollyon.

Contemporary English Version
Their king was the angel in charge of the deep pit. In Hebrew his name was Abaddon, and in Greek it was Apollyon.

New American Bible
They had as their king the angel of the abyss, whose name in Hebrew is Abaddon and in Greek Apollyon.

Douay-Rheims Bible
A king, the angel of the bottomless pit (whose name in Hebrew is Abaddon and in Greek Apollyon, in Latin Exterminans).

A king, the angel of the bottomless pit (whose name in Hebrew is Abaddon and in Greek Apollyon, in Latin Exterminans).

they had.

Revelation 12:9 And that great dragon was cast out, that old serpent, who is called the devil and Satan, who seduceth the whole world. And he was cast unto the earth: and his angels were thrown down with him.

John 12:31 Now is the judgment of the world: now shall the prince of this world be cast out.

John 14:30 I will not now speak many things with you. For the prince of this world: cometh: and in me he hath not any thing.

John 16:11 And of judgment: because the prince of this world is already judged.

2 Corinthians 4:4 In whom the god of this world hath blinded the minds of unbelievers, that the light of the gospel of the glory of Christ, who is the image of God, should not shine unto them.

Ephesians 2:2 Wherein in time past you walked according to the course of this world, according to the prince of the power of this air, of the spirit that now worketh on the children of unbelief:

1 John 4:4 You are of God, little children, and have overcome him. Because greater is he that is in you, than he that is in the world.

1 John 5:19 We know that we are of God and the whole world is seated in wickedness.

the angel.

Revelation 9:1 And the fifth angel sounded the trumpet: and I saw a star fall from heaven upon the earth. And there was given to him the key of the bottomless pit.

Abaddon.

John 8:44 You are of your father the devil: and the desires of your father you will do. He was a murderer from the beginning: and he stood not in the truth, because truth is not in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father thereof.