The Collaborative International Dictionary of English v.0.48:

Earthling \Earth"ling\, n. [Earth + -ling.]
   An inhabitant of the earth; a mortal.
   [1913 Webster]

         Earthlings oft her deemed a deity.       --Drummond.
   [1913 Webster]

WordNet (r) 3.0 (2006):

earthling
    n 1: an inhabitant of the earth [syn: tellurian, earthling,
         earthman, worldling]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "earthling":
   Adamite, antichristian, being, body, cat, chap, character,
   creature, customer, duck, fellow, groundling, guy, hand, head,
   homo, human, human being, iconoclast, idoloclast, individual,
   irreligionist, joker, life, living soul, man, materialist, mortal,
   nose, one, party, person, personage, personality, single, somebody,
   someone, soul, tellurian, terran, worldling