The Greek proper noun Apollyon (G623) means Destroyer or Destruction — the active participle of apollymi (G622, to destroy/perish). It appears once in the New Testament, in Revelation 9:11, as the name of the angel of the Abyss — the king of the demonic locusts unleashed from the bottomless pit during the fifth trumpet judgment. John provides both the Hebrew name (Abaddon) and the Greek equivalent Apollyon, confirming their equivalence.
The naming of the destroyer in Revelation 9:11 is a revelation of Satan's essential nature and agenda. Jesus identifies the devil as one who 'comes only to steal and kill and destroy (apolesē)' (John 10:10), while Christ Himself comes to give life abundantly. The contrast between Apollyon (destroyer) and Christ (life-giver) defines the spiritual conflict of the entire age. The Hebrew name Abaddon (destruction/the underworld) appears in Job and Proverbs as a synonym for Sheol, the realm of the dead. Revelation's use of Apollyon identifies this power with the final demonic assault before Christ's return — a ruler whose time is limited by the sovereign God who holds the keys of death and Hades (Revelation 1:18).