The world of Cantabria is home to many different creatures, mostly inimical to human life - and many, even worse, visit from time to time!
Here may be found descriptions and details of such creatures as may be encountered: D&D Monsters
Creatures known to dwell in Cantabria include: Ankheg, Bugbears, Bulette, Cockatrice, Ice Devils, Dragons (Chromatic & Metallic), Giant Eagles, Gargoyles, Ghouls, Ghasts & Sea-Ghouls, Giants of many types, Goblins (& Half-Goblins), Gorgons, Kobolds (of differing types, associated with chromatic dragons), Lizardfolk, Lycanthropes, Mimics/Trappers, Mules (though rare and expensive!), Ogres (& Half-Ogres), Orcs (& Half-Orcs), Otyugh, Rats, Skeletons, Spiders (both Monstrous and Phase), Trolls, Vampires, Will-o-Wisps, Wolves, Worgs, Zombies and Ki-Rin (a form of half-celestial goat, known for their capricious, cowardly and untrustworthy nature).
(Whereas looking up monsters in the manual would normally be naughty, these are unlikely to be the actual stats used for denizens of Cantabria. Hence these can represent 'rumoured' abilities of such creatures, determined during camp-fire discussions by adventuring characters. It might also be an inspiration for our GM! - SJW)