Alien

ajeno

(very unfamiliar, strange)

alienígena

(not belonging to the same country)

alienígena

(pertaining to extraterrestrial life)

alienígeno

(very unfamiliar, strange)

extraterrestre

(pertaining to extraterrestrial life)

advena

(person, etc. from outside)

alienígena

(life form of non-Earth origin)

desconocida

(person, etc. from outside)

desconocido

(person, etc. from outside)

extranjera

(foreigner)

extranjero

(foreigner)

extraterrestre

(life form of non-Earth origin)