So I picked up a copy of SoI, and the system generation rules are fairly easy to get heads around, and I have started using it to create planets for my OW group to play around on, but as I am in the progress of writing a RT game, I wanted to start filling my shiny new planets with weird and wonderful Xenos. I noticed that it mentions using the Koronus Bestiary to create more detailed descriptions of pre-industrial and primitive clans, but I would like my players to come across more advanced species than that, as my players tend to just start conquering planets with low levels of technology, and avoiding anyone that could pose any significant threat to them. 

Now I want them to start actually interacting with advanced civilisations and instead of just having them interact with the normal none-human species, I want to create some other creatures for them. I can't find anywhere a source for creating an advanced Xenos species, not necessarily their technology, just the actual looks, skills, talents & traits etc. can anyone recommend any good sources for this? The koronus bestiary one just isnt detailed enough for me. 

So 93 page views and not a single response? A no would have been nice. 

Well, you could do what GW does and "reimagine" other people's work…..

I have quite a lot of Starwars rpg stuff including an atlas of the universe, locations books and many essential guides detailing races and animals and droids…

All of which are excellent inspiration for WH40K and because they are from a different setting, they easily give off a "xenos" vibe….. Or you can use the B2 battle droid as an example of the legendary 'men of iron' still serving a lost human civilization….

Another idea is to run with fantasy settings from books. How about a world where armies consist of dragon riders?