Apollyon:

[Chronos]

Apollyon appears in the New Testament (Book of Revelation 9:7 – 11) leading the locust-like swarm of demons that will be released in the End Times:

7. In appearance the locusts were like horses arrayed for battle; on their heads were what looked like crowns of gold; their faces were like human faces, 8. their hair like women's hair, and their teeth like lions' teeth; 9. they had scales like iron breastplates, and the noise of their wings was like the noise of many chariots with horses rushing into battle. 10. They have tails like scorpions, and stings, and their power of hurting men for five months lies in their tails. 11. They have as king over them the angel of the bottomless pit; his name in Hebrew is Abaddon, and in Greek he is called Apollyon.
The name, in Greek "Destroyer" (Απολλυων, from απολλυειν, to destroy) is cognate with the Hebrew Abaddon (lit. "place of destruction," but here personified) and the Greek god Apollo, also a "destroyer" in his aspect of controlling pestilence, though the composite monstrosity that is Apollyon is distinctly Babylonian and Persian, not Hellenic, in inspiration. Apollyon seems to be equated in Revelation with the Beast. The term "Apollyon" was often associated by early Christians with The Devil, and fancifully described, and is still used as an alternative name for him.

Apollyon is the "foul fiend" who assaulted Christian on his pilgrimage through the Valley of Humiliation in John Bunyan's great allegory The Pilgrim's Progress. The identification with the Asmodeus of Tobit iii. 8 is erroneous.

The Christian view which stands in contrast to the prevalent perception of Apollyon as a demonic figure. Rather than seeing the character of Apollyon as original to the book of Revelation, this view identifies Apollyon with the "destroyer" who carries out the tenth plague (the death of the firstborn) described in the Exodus account (Exodus 12:23). This view receives support from a subsequent reference to the "destroyer of the firstborn" by the anonymous author of the book of Hebrews, who in 11:28 describes the protection of Moses and Israel from God's destructive agent. In this instance the author makes reference to ο ολοθρευων (the destroyer), a participle form sharing a common root with Απολλυων. This alternate view would also explain why both Hebrew and Greek forms of the angelic name are supplied by the author of Revelation.

While some believe apollyon to have the key to the abbyss revelation clearly states an angel opens the abbyss and lets appolyon and the fallen angels out. Some also belive apollyon to be michael but this is incorrect as proven below.

"And there was war in heaven. Michael and his angels fought against the dragon, and the dragon and his angels (fallen angels) fought back." Rev 12:7

We know Apollyon is the beast that gains it's power from the dragon who leads the fallen angels into war because if we put the prophecy in context it's obvious.:

"They had tails and stings like scorpions, and in their tails they had power to torment people for five months. They had as king over them the angel of the Abyss, whose name in Hebrew is Abaddon, and in Greek, Apollyon." - Revelation 9:10-11

Micheal shall lead the angels and Apollyon shall lead the fallen after the 5 months of torment.

"REV:9:3 Then from the smoke came locusts on the earth, and they were given power like the power of scorpions of the earth; 4 they were told not to harm the grass of the earth or any green growth or any tree, but only those of mankind who have not the seal of God upon their foreheads; 5 they were allowed to torture them for five months, but not to kill them, and their torture was like the torture of a scorpion, when it stings a man. 6 And in those days men will seek death and will not find it; they will long to die, and death will fly from them. "

Demonic monsters are released which fly like locusts (Exodus 10:12-20; Joel 1:4, 2:4-14) and sting like scorpions (Ezekiel 2:6, Lk 11:12).

The book of revelations was written by john who liked getting multiple views of the same event. Giving us a more detailed view on the order of events. An example of this is:

Revelation 9:3-11 talking in depth of the demons and there leader apollyon. Who gains his power from the Dragon (satan).

"REVELATION 11:7 When they [the two witnesses] have finished their testimony, the beast that comes up out of the Abyss will make war with them, and overcome them and kill them"

"REVELATION 17:8 The beast that you saw was, and is not, and is to ascend from the bottomless pit and go to perdition"

REVELATION 13:1 Then I stood on the sand of the sea. And I saw a beast rising up out of the sea . (The ocean depths is thought by the jewish to be the abbyss).

This all tells the same story as in 9:3-11. This would mean the man of sin , son of perdition , beast of the end of days is apollyon.

"falling away of those who have professed to be Christians has come, and the man of lawlessness is revealed, who is the son of perdition" - 2 Thessalonians 2:3

"While I was with them, I kept and preserved them in Your Name [ [Albert Barnes, Notes on the New Testament.] in the knowledge and worship of You]. Those You have given Me I guarded and protected, and not one of them has perished or is lost except the son of perdition [Judas Iscariot--the one who is now doomed to destruction, destined to be lost], that the Scripture might be fulfilled. [Ps 41:9; John 6:70 ] "

"And the fifth angel blew his trumpet, and I saw a star fallen from heaven to earth, and he was given the key of the shaft of the bottomless pit; 2 he opened the shaft of the bottomless pit and from the shaft rose smoke like the smoke of a great furnace, and the sun and the air were darkened with the smoke from the shaft. " -Revelation 9:1

Using logic we can tell apollyon is obviously not michael as micheal is to lead the angels into battle against the fallen after the 5 months of torture is up. While apollyon is the leader of the fallen. The son of perdition and the man of sin. He is the beast mentioned in the end of days . As mentioned in John 17:12 Judas is the son of perdition thus it would seem apollyon is judas. He who betrayed jesus christ his teacher and the son of god and then killed himself. Is the man of sin.