Oh, I've never actually played D&D either. I'm mainly familiar with it through its wiki (which I occasionally browsed for a while some time ago for some unfathomable reason) and the Neverwinter Nights-series.
I know that both Danish and Norwegian folklore have devil[I]s[/I] (plural) in them that are somewhat similar, though Danish folklore does occasionally have some very odd ways of labeling things. Nearly every creature in it is called either "troll" or "witch", with rarer mentions of dragons (such as in the legend of Beowulf) and devils. The labels don't mean much, though, since the descriptions vary so wildly that one can't really say what any of them are supposed to be. A witch can just as easily be a human as a completely inhuman monster, and trolls can be everything from humanlike forms to serpents. Going further back in time, our folklore instead starts to feature a lot of giants, jotun, lindworms and, to a much greater extent than relatively recent folklore, heroes. The only "dragon" we originally had was Nidhogg (which pretty much doubled as the Norse version of Hell, as it ate the worst criminals); the rest were lindworms, which were every bit as formidable as any dragon I've ever read about (perhaps even more so, as some lindworms are stated to be unable to die, spurring the Christian saviors (oh yes) to built churches on top of them and hallow the ground around them in order to weaken and imprison them). There were a lot of other old Norse creatures of myth and legend, of course (such as draugr, which the world was reminded of recently), but none appear as often as those.