Is the angel of the bottomless pit Satan?
The angel of the bottomless pit is not Satan; he is called Abaddon in Hebrew and Apollyon in Greek, meaning destroyer. He is likely one of Satan's cohorts or lieutenants, though some may think he is Satan. The text presents him as king over the locust-like creatures.
Les teaches from Revelation 9 that the creatures coming out of the bottomless pit have a king over them, the angel of the bottomless pit. His name in Hebrew is Abaddon and in Greek Apollyon, which means the destroyer. Les explains that beyond this, we don't know who the angel is. He says, 'It's not Satan, I'm quite sure. He's probably one of Satan's cohorts.' Some may feel this is Satan, but Les thinks it's one of his lieutenants. These creatures are described as having tails like scorpions with stings, able to hurt men for five months, and their sound is like many chariots. This is the first woe, with two more to come. The sixth angel then sounds, and a voice from the four horns of the golden altar releases four angels bound at the Euphrates, which connects back to the Tower of Babel in Genesis 10.
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.