Parallel
Revelation 9:11
Nestle 1904 Greek New Testament · Berean Standard Bible
ἔχουσιν ἐπ’ αὐτῶν βασιλέα τὸν ἄγγελον τῆς ἀβύσσου ὄνομα αὐτῷ Ἑβραϊστί Ἀβαδδών καὶ ἐν τῇ Ἑλληνικῇ ὄνομα ἔχει Ἀπολλύων
They were ruled by a king, the angel of the Abyss. His name in Hebrew is Abaddon, and in Greek it is Apollyon (note: Apollyon means Destroyer.).