Aliens adjectives are listed in this post. Each word below can often be found in front of the noun aliens in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing ALIENS.
certain, criminal, dangerous, enemy
evil, hostile, illegal, immigrant
japanese, legal, many, more
nonresident, only, other, resident
space, such, undesirable, undocumented
Hope this word list had the adjective used with aliens you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.
Horrible
Hazardous
slimy,disgusting,sticky,different,not a human
Slimy green
scary