Barlowe's Guide to Extraterrestrials is a 1979 science fiction book by artist Wayne Barlowe, with Ian Summers and Beth Meacham (who provided the text). It contains his visualizations of different extraterrestrial life forms from various works of science fiction, with information on their planetary location or range, biology, and behaviors, in the style of a real field guide for animals, such as Roger Tory Peterson's guide to birds of North America. It was reprinted in 1987.
Some species from Space Opera Settings
Athshean? - Ursula K. Le Guin's The Word for World is Forest ?(1975), Hainish Universe?
Guild Steersman? - Frank Herbert's Dune?, Dune Universe
Ixtl? - A. E. van Vogt's? The Voyage of the Space Beagle?, Aliens Universe?
Merseian? - Poul Anderson's? Ensign Flandry?, Technic History?
Pierson's Puppeteers - Larry Niven's Known Space series
Regul - C. J. Cherryh's The Faded Sun: Kesrith, Alliance Union
Riim? - A. E. van Vogt's? The Voyage of the Space Beagle?, Aliens Universe?
Thrint - Larry Niven's Known Space series
Tran? - Alan Dean Foster's? Icerigger?, Humanx Commonwealth?
Barlowe's Guide describe many more alien races, but most of them are not relevant to this site.
Other sites: Wikipedia,