Is this king the same angel as the star of Revelation 9:1?
Revelation 9:11 (ESV)
11They have as king over them the angel of the bottomless pit. His name in Hebrew is Abaddon, and in Greek he is called Apollyon.
There is no reason within the text itself to make this connection. As the Lord has not clearly connected the angel of Revelation 9:11 to the angel of Revelation 9:1, there is nothing to be gained by equating the two.
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.