aardwolf!
hyrax!
chupacabra!
rust monster
Jabberwock
umber hulk
floating eye
owlbear
quasit
hydra (either the one from Greek mythology or the weird nifty sea creature)
chimaera

The list of "I have no idea what these things are but what the heck":
rothe
leucrotta
titanothere
baluchitherium
wumpus

What's that creature in nethack that stabs your shins with a pin? A xat?

I'll let you know if I think of any more.

Oh no, poor cat. I hope the vet is able to do something for her.