Angels and demons inhabit the Universe. They are what we would call "aliens".
Some day satan is going to
COME DOWN to earth visibly.
7: And there was war
in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
8: And prevailed not; neither was their place found any more in heaven.
9: And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was
cast out into the earth, and his angels were cast out with him.
10: And I heard a loud voice saying in heaven, Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast
down, which accused them before our God day and night.
11: And they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death.
12: Therefore rejoice, ye heavens, and ye that dwell in them. Woe to the inhabiters of the earth and of the sea! for
the devil is come down unto you, having great wrath, because he knoweth that he hath but a short time.
Rev. 12:7-12
One day many aliens will come to the Earth. They will mightily deceive men.