We are introduced to this character in Revelation 8. He is significant, so here is a bit more detail about this angelic being.
Who is he? It appears that he is the only character in the Bible worse than Satan. Let's look at the scriptures he appears in to see if we can shed some light on him. He appears by name seven times. Three times in Job, twice in Proverbs, once in the Psalms, and once in Revelations. In Revelations, Abaddon is also described as the angel of the bottomless pit.
I will run through each reference and give a small description. Job 26 “Sheol is naked before God, and Abaddon has no covering.” Sheol is the realm of the dead, and Abaddon suggests that Sheol and where Abaddon lives are different places. The word Abaddon in some texts is described as destruction.

Job 28 talks about wisdom when we come across Abaddon this time. Job 28:22, Abaddon and Death say, We have heard a rumour of it with our ears. Death is one of the rulers of Sheol and a demonic being. So Abaddon is also a spiritual being. That Abaddon and Death are close to each other in the depths of the earth. This place that Abaddon dwells in can hear what is going on earth. They hear and have ears, which is a very physical thing. Job 31:12 says, “For that would be a fire that consumes as far as Abaddon,” This suggests a place that is far away or difficult to reach.
Now read Psalm 88:11. Is your steadfast love declared in the grave, or your faithfulness in Abaddon? I would assume that these characteristics are the opposite of the conditions in this place. Like Hades and Death, Abaddon also gives his name to this place. This place has the trait of unfaithfulness.
Proverbs 15;11 Sheol and Abaddon lie open before the LORD; how much more the hearts of the children of man! This is talking about where God can see. He sees everywhere and everything. Sheol and Abaddon are two different places, both under the ground.

Let us summarize what we can see so far. That Abaddon is both a person and a place. To be more precise, Abaddon rules a place that gets to be called by the ruler's name. He can hear what is going on in the world, even though it is far away. There is some form of physical link. The main characteristic is that it is a place of faithlessness.

Now, Revelations 9:11 They had as king over them the angel of the Abyss, whose name in Hebrew is Abaddon and in Greek is Apollyon (that is, destroyer). A star fallen from heaven is given the key to the bottomless pit. This is not Satan because he had already been thrown out of heaven well before the tribulations began. Four of the calamities of the tribulation have already happened. He has a key to unlock the abyss. That would make it a prison. It is not part of Hades and Death's Sheol, as that is the realm of the dead. That is a place where people go, not Demonic beings. Not that there aren't spiritual beings, that exist only in Sheol. God created the heavens and the earth in the beginning. Not, the heavens, the earth, and the abyss. This makes the Abyss a part of a heaven, and we know it is not the second heaven or the kingdoms. It is not part of Paradise, so that only leaves it as a prison in the first heaven, or Sheol. The first heaven is below us, the earth and the second heaven are around us, and the third heaven is above us.

If we go to Revelations 17, we find that the beast that the woman rides came out of the bottomless pit. We know that the bottomless pit is a prison, and it has only just been opened. It is highly unlikely that other powerful fallen angels have come out at the same time and not gotten a mention. Moreover, they are not only in this prison, are in chains. This beast is also described as “the beast who once was, and now is not, an eighth king. He belongs to the seven and is going to his destruction.” I find this interesting, as there are only a limited number of opportunities for this to happen. The earliest mentions of him already have him in the Abyss. The only place I can see where he could exist on earth was before the flood. The angels that were the fathers of, as Genesis says, “these were the mighty men who were of old, the men of renown”. For their trouble, they got thrown into the Abyss for not keeping their place. Abaddon must have been one of these, and probably the most powerful of them. In the world, men are often accused of thinking with their genitals. It seems these angels have the same problem. It looks like we have learned where that folly came from.

One of his names is “Angel of the Abyss. Why is he called a beast? He may not have the shape of a human, like an angel. The Seraphs and Cherubim are types of angels and intelligent beings, but John called them beasts earlier in Revelations because they do not have human shapes. That seems highly unlikely. It must be some reference to his spiritual nature. Abaddon actually gets to walk our earth, and it will be astonishing to see. This means that from the Abyss, he must be able to impose some effect on the world. He has some authority in cosmic geography. Firstly, in Babylon and on through to when he is released from the pit and has direct control. Job 28:22 says he can hear what is happening on the earth; it is only a small step to believe he can do more than that. Once he is out, he becomes one of the eight heads. The USA is the seventh head and has been destroyed by fire. The Antichrist has arisen and has a lot of influence over the whole world. The great cities of the world still exist, and Abaddon is on earth and has full control. It is in this situation that he kills the two servants. Either Moses and Elijah, or two people who have the ministries of Elijah and Moses.
The gap in the first heaven that leads to the bottomless pit. Where is it? I believe that this CERN large hadron collider is the door. The site itself used to have a temple to Apollo, or Apollyon, the destroyer. At the front entrance, there is a statue of the Indian god Shiva. The god is known as the destroyer or destruction, which is also the name of Abaddon.
So, that’s Abaddon, the most evil being to ever roam the earth. Satan may be the father of lies and the main protagonist against the works of Jesus, but for pure evil, Abaddon is the man. Abaddon, the Antichrist, and the False Prophet are the first recorded beings thrown into the lake of fire. Evil does have its rewards.