Revelation 9 11
Ruling over them as their king was the angel of the Abyss who is called Abaddon in Hebrew and Apollyon in Greek.
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YLT Revelation 9:11and they have over them a king — the messenger of the abyss — a name is to him in Hebrew, Abaddon, and in the Greek he hath a name, Apollyon.
CSB Revelation 9:11They had as their king the angel of the abyss; his name in Hebrew is Abaddon, and in Greek he has the name Apollyon.
KJV Revelation 9:11And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon.