Revelation 9:11

Overview - Revelation 9
At the sounding of the fifth angel, a star falls from heaven, to whom is given the key to the bottomless pit.
He opens the pit, and there come forth locusts like scorpions.
12 The first woe past.
13 The sixth trumpet sounds.
14 Four angels are let loose, that were bound.
Treasury of Scripture Knowledge

Revelation 9:11  (King James Version)
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.

they had
12:9 John 12:31 ; 14:30 16:11 2 Corinthians 4:4 ; Ephesians 2:2 ; 1 John 4:4 ; 5:19

the angel

that is, a destroyer.
John 8:44