Revelation 9:11
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.
Cross-reference
Revelation 9:1
Parallel
In Revelation 9:1, the angel receives the key to the abyss — this verse names that same angel as Abaddon.
Revelation 9:3
Parallel
Revelation 9:3 introduces the locusts that emerge from the smoke; this verse names their king Abaddon, the angel of the abyss who commands them.
Revelation 20:2
Related theme
Revelation 20:2 shows Satan bound in the abyss — the same abyss over which Abaddon rules as king in this verse.
John 8:44
Related theme
In John 8:44, the devil is a murderer from the beginning — his destructive nature matches Abaddon's name meaning destruction.