Foo-critters doesn't sound right, but I'm less sure about that than some of the other things that have been mentioned here.

I didn't know there was a
Planescape Monstrous Compendium. I guess in my obsessive accumulation of D&D material over the decades, that's one I overlooked. But, If I've never seen or heard of it, then I can't have taken anything from it for my campaigns.
In 2007 I packed up all my D&D stuff (along with everything else I own) and moved from CT to WA. I've found and unpacked most of what I used to have, but there are gaps. For example, I own every printed issue of Dragon Magazine and Dungeon Magazine ever published, but I can't find the first 20+ years of them. I know the movers stole some of my stuff, I'm just hoping they turn up. Can't imagine why the movers would take only part of my collection.
Sorrowdusk, you mentioned "Rakasta". If you meant "Rakshasa", then no, not them. These cats are not humanoid at all.
I want to thank everybody for trying. I'll keep checking back in case someone comes up with anything else.