The supplemental rules forming about a third of the book were largely outmoded by the revised edition of Supers.

Armintrout, William A. Barton, Steve Jackson, Creede Lambard, and Sharleen Lambard, with a cover by Michael Whelan, and was published by Steve Jackson Games in 1990 as a 128-page book.

[3] David L. Pulver reviewed GURPS Aliens for Challenge #49.

[1] Pulver comments in his conclusion: "GURPS Aliens' imaginative array of extraterrestrial races coupled with its lucid organization makes it a pleasure to read and to use.

I have no hesitation in giving it a whole-hearted recommendation, not only as an invaluable sourcebook for GURPS, but as a useful source of ideas for any science-fiction RPG.