Well according to standard Christian theology the antiChrist has a connection to the devil. Since the Devil is bound here on earth I am not sure how a apce alien could fit the bill.
Well Satan was not originally from Earth either, and right now he's the "prince and power of the air" and is not bound to the Earth. That's why in Job he and his corrupted angelic host go to Heaven and talk to God when God asks Satan the question: "What do you think about my servant Job?"
Revelation 12:9
"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."
So-called Space Aliens are simple apparitions of demons. The connection is simple and direct.