Common knowledge about squirrels is that they are basically furry rats. Yes, they are adorable in an amnesiac sort of way, what with their inability to remember where they buried their nuts, but the modern squirrel is not typically considered a manifestation of anything monstrous. Interestingly, much like Coca-Cola and Pop Rocks, if you combine Viking aesthetics with squirrels, you produce a malevolent little rodent called Ratatoskr (“Drill Tooth” in Old Norse) that spends his days spreading malicious gossip and trying to start a fight between the eagle at the top of the World Tree Yggdrasil and the angry Wyrm beneath called Níðhöggr, generally with phrases like, “Did you hear what he said about your mother?”
via Ratatoskr and Meeko: Spiteful Squirrels of Norse and Wabanaki Mythology | EsoterX.