Aliens

(from the back of the book):

To seek out new life and new civilizations...

The Suliban have infiltrated this book. So have to Gorn. And the Flaxians. And they've brought friends, all complete with full game statistics so you can pit them against one another in your Star Trek RPG series.

Aliens includes:

58 alien races, ranging from near-humanoids such as the Ekosians to bizarre entities such as the Q, the Horta, and the Medusans.
New species-specific traits, weapons, technology, and skills, as well as new background rules to handle characters raised by alien cultures.
Coverage of aliens from all eras: Whether the Gorn from the original series, the Axanar from Enterprise, or the Vorta from Deep Space Nine, it's in this book.