Moutain lions are the best. The way they jump on your head is sooooo cool.
I enjoy casting invisibility as they jump and watch the confused look on their snatta cat faces.
Will-o-Wisps are annoying. They keep sneaking up on me when I think I am safe.
Humans annoy me too. I wish I could use normal soul gems on them. Nothing worse than wasting a charge on my sharp sword....
I hope Skyrim is overrun by Winter Wolves, Frost Giants, Mammoths, Yeti, Ogre, Bugbear, Manticore, Ettin, Forlarren, Hydra and Lycanthrope.