New Enemies?

I’m a new GM and starting to plan out the overarching story a bit, at least for a year in game. Has anyone here ever made a new enemy similar to the Weasels? Like, putting a Fox at the head of an army or something?

I tend to like my animals as animals—and only use the weasels as the other “intelligent” people. But I certainly don’t see any harm in it!

I have been in this one one-shot game where shrews were made little more intelligent than the average animals. They didn’t have the tech similar to mice but used stone tools etc. Then I remember seeing in these forums a mission suggestion where moles have created a complicated underground civilization hiding from other intelligent animals.