"4And it was commanded them that they should not hurt the grass of the earth, neither any green thing, neither any tree; but only those men which have not the seal of God in their foreheads. 5And to them it was given that they should not kill them, but that they should be tormented five months: and their torment was as the torment of a scorpion, when he striketh a man. 6And in those days shall men seek death, and shall not find it; and shall desire to die, and death shall flee from them.
7And the shapes of the locusts were like unto horses prepared unto battle; and on their heads were as it were crowns like gold, and their faces were as the faces of men. 8And they had hair as the hair of women, and their teeth were as the teeth of lions. 9And they had breastplates, as it were breastplates of iron; and the sound of their wings was as the sound of chariots of many horses running to battle. 10And they had tails like unto scorpions, and there were stings in their tails: and their power was to hurt men five months. 11And 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."
https://biblehub.com/kjv/revelation/9.htm
"In Revelation, Abaddon is the king of the abyss or bottomless pit who commands an army of locusts. According to Revelation 9:1-11, after the fifth angel sounds his trumpet, a star falls from heaven and opens the bottomless pit. A storm of smoke arises, and from the smoke, a plague of locusts emerge to torment, but not kill, men who lack the seal of God on their foreheads for five months."
https://www.deliriumsrealm.com/abaddon/
"There are several names in the Bible for Satan and his minions. One of these is “the Apollyon,” which might refer to Satan or to a high-ranking demon. The name “Apollyon” is the Greek for “Abaddon” meaning “Destroyer.”"
https://www.christianity.com/wiki/christian-terms/what-is-the-apollyon.html
"Abaddon/Apollyon is likely one of Satan’s underlings, a destroying demon and one of the “rulers,” “authorities,” and “powers” mentioned in Ephesians 6:12."
https://www.gotquestions.org/Abaddon-Apollyon.html
"The Greek name used by the apostle John to translate the Hebrew “Abaddon” at Revelation 9:11. Apollyon means “Destroyer,” and is given as the name of “the angel of the abyss.” Though most reference works apply this name to some evil personage or force, the whole setting of the apocalyptic vision is to the contrary, as it consistently portrays angels being used by God to bring woes upon His enemies."
https://wol.jw.org/en/wol/d/r1/lp-e/1200000308