Revelation 9:9-11

Young's Literal Translation

⁹ and they had breastplates as breastplates of iron, and the noise of their wings [is] as the noise of chariots of many horses running to battle;

¹⁰ and they have tails like to scorpions, and stings were in their tails; and their authority [is] to injure men five months;

¹¹ and they have over them a king -- the messenger of the abyss -- a name [is] to him in Hebrew, Abaddon, and in the Greek he hath a name, Apollyon.