From Lexicanum

Xenos worlds are non-human and non-Imperial worlds inhabited by alien races. Humanity is just one of many races in the galaxy, but none are so widely distributed or so numerous as humans. Most alien races occupy only a single world or a small group of worlds. The majority of aliens are comparatively primitive, peaceful or powerless, and of little interest to humanity. Only a few alien races are powerful, aggressive and possess technology which rivals that of the Imperium. Of these, the most common are the Orks, Eldar, Tyranids and Tau.

Worlds of the Galaxy

Imperium	Adeptus Astartes Homeworld • Agri World • Cardinal World • Civilised World • Dead World • Death World • Desert World • Feral World • Feudal World • Forge World • Hive World • Ice World • Industrial World • Jungle World • Knight World • Mining World • Ocean World • Paradise World • Penal World • Research Station • Shrine World
Xeno	Xenos World • Daemon World • Exodite World • Tomb World • Maiden World • Crone World • Ork World • Tau Empire • Craftworld

Sources

• WD139, WD140, White Dwarf 139 and 140