Who is the king over the locusts in Revelation 9:11?
The king over the locusts is the angel of the bottomless pit. His Hebrew name is Abaddon, and his Greek name is Apollyon, which means the destroyer. He is not Satan, but probably one of Satan's lieutenants, though his identity beyond that is not given.
Les explains that in Revelation 9 the locusts are described as swarming and roaring; in the Middle East they can cloud out the sun, and their wings sound like many chariots. They have tails like scorpions and power to hurt men five months. Verse 11 says they had a king over them, the angel of the bottomless pit, named Abaddon in Hebrew and Apollyon in Greek, meaning the destroyer. Les says beyond that we do not know who this angel is. He is quite sure it is not Satan, but probably one of Satan's cohorts or lieutenants; some may feel it is Satan, but he thinks it is one of his lieutenants. Verse 12 then notes one woe is past, with two more to come.
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.