Well, obviously wolves, werevolves, bears, spriggans, horkers... Kinda expect them, Solstheim memories. Plus I hope they'll manage to work in a slight daedra infestation, nothing to showy, but I would miss those too.

Okay, one pick ? I guess I would really like an expansion on Rieklings.

rofl he's a monster!

Having gone through the wiki to make this list semi-credible I've decided thusly.

Arena: Medusa http://www.uesp.net/wiki/Arena:Monsters
Daggerfall: Dragonling http://www.uesp.net/wiki/Daggerfall:Bestiary
Battlespire: Dark Seducer http://www.uesp.net/wiki/Battlespire:Bestiary (it has wings)
Redguard: Vermai http://www.uesp.net/wiki/Battlespire:Bestiary
Morrowind: Winged Twilight http://www.uesp.net/wiki/Morrowind:Daedra
Tribunal: Durzogs http://www.uesp.net/wiki/Tribunal:Durzogs
Bloodmoon: Rieklings http://www.uesp.net/wiki/Bloodmoon:Creatures
Oblivion: Minotaur http://www.uesp.net/wiki/Oblivion:Creatures
Shivering Isles: Shambles http://www.uesp.net/wiki/Shivering:Creatures

-Others include: Flesh Astronach, goblins, trolls, slaughterfish, mud crabs, bears, snow bears, grahls, ogres, saints, clannfer, scamps, rats, cougars, wolves ...
and a host of other things that the designers can cook up.

A true monster.

It wouldn't be TES if it didn't have rats.