“And 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.”
King James Version (KJV)
9:11 And they have over them a king - One by whom they are peculiarly directed and governed. His name is Abaddon - Both this and Apollyon signify a destroyer. By this he is distinguished from the dragon, whose proper name is Satan.
Re 9:11 They had a king over them. The real king was not the star, but the power of the bottomless pit. Apollyon. The destroyer; either the devil or one of his angels.