If you look at some old classic Sci-fi, Pohl Anderson's Flandry and Polesotechnic League stories there are tons of good old-fashioned aliens that are good for adapting into Traveller.
Aslan: you could use the Tigery from Ensign Flandry...a low-tech seafaring cat-like race that lives on a large, heavy atmosphere wolrd. Primitive neobarbarians, but if you advance them a bit to space-faring they would be really interesting. Matriarchal, but both sexes fight...
Vargr: In Hunters of the Sky Cave, Anderson introduces the Ardizirho..a wolf-like race that sounds socially suspiciously like the Vargr, but individually and physiologically are very different.
Borthudians: Again, a cat like race from the poleosotechnic league stories that is described as humanoid but panther-like (no fur but black and with cat-like eyes and mannerisms), barbarian but star-faring (they have pagan idols burning inscense on the bridge) and are like a sci-fi Barbary Pirate type.
The list goes on....
Myself, I came up with the Prox in my original vintage 77 campaign long before the Vargr appeared. Marsupial hyena like bipeds. TL-11 Loyalty to family group supersedes loyalty to clan or any larger group Females are non-intelligent (nod to the Kzin) and populations pressure among males encourages them to strike out and gain more territory to set up their own extended family groups. As I have evolved them in my campaign they have grown into two main lines: the ones who went legit and run merchant houses, and the ones who run most of the smuggling/organized crime/pirating groups based mainly off rogue planets and moons hidden away here and there. Either way, the family is everything.
I never like the Vargr myself, nor the Aslan..but then I never much cared for the OTU: too civilised. Not enough sword n' blaster.
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