KoolMoDaddy-O
Explorer
It is difficult to parse the 1e barbarian, and hence its 5e descendants, from Howard's Conan.
I guess that depends on whether or not Gygax wanted the vibe of his game to match what happened in a standard Fafhrd and Grey Mouser story. For instance, I see a lot more of them in D&D from just an actual game play standpoint than I do Conan, I.E. little humor, exceptionally competent warrior who could handle everything thrown at him. Fafhrd and GM were much more lovable screwups. The style of the adventures he published just seemed to me more appropriate to them than other books that inspired him.I think @SothFan is actually asking about how the influences made it into the game, and in what form (which is why I started with the easy one of Vancian casting).
I am actually curious about how the thief came to be and what material directly influenced its various abilities. By the time I discovered D&D in the early 80s, the thief was a staple. But it was not in the first iteration of the game so something must have inspired it.
The audio version by Bronson Pinchot is also pretty great. It turns out he has more voices than just Cousin Balki.And also just a really good book. A lot of the Appendix N stuff is so-so at best, but 3H3L is genuinely quality fantasy.
Gygax did not come up with the Thief as a class. If memory serves someone did, their friend put a different version out in a zine and Gygax saw that and came up with his own mechanical spin in OD&D Supplement I Greyhawk.I am actually curious about how the thief came to be and what material directly influenced its various abilities. By the time I discovered D&D in the early 80s, the thief was a staple. But it was not in the first iteration of the game so something must have inspired it.
I'd say Hugi was a big inspiration for D&D dwarves. The full sweep of 1e dwarf underground powers of detecting sloping passages and depth underground and such was straight out of Three Hearts and Three Lions. That has continued in modified form throughout editions for dwarves while gnomes lost it long ago.Poul Anderson's Three Hearts and Three Lions was very influential. The main influence for the Paladin archetype, regenerating trolls, Hugi the dwarf was an inspiration for D&D gnomes, and (along with Moorcock) Law and Chaos as cosmic teams.
Also similar to the D&D Balrog which was later renamed the Balor, treants were originally straight ents until they did the renaming.Lord of the Rings: Playable dwarves, elves, and wizards. The existence of halflings and orcs, half-orcs, and half-elves. Cursed magic items. Rangers. The quintessential idea of the adventuring party. Wights and Wraiths (undead). Exploring dungeons (Moria). At least 1 type of demon (the “balor” who descends from the balrog)
This proves to have a more complicated question than you might think. Over the decades, I’ve had several surreal exchanges with Old Geezer and others from the ur-D&D scene about what it means to have something as an inspiration. They have all assured me, clearly, that it does not mean characters being able to do things protagonists in inspirational stories do, nor events like those in the inspirational stories happen. This seems so weird to me that I’ve asked for clarification in follow-ups, to make sure I wasn’t misunderstanding. Because when I say that Game X has story Y as an inspiration, I mean get it has made an effort to provide support for characters and events like Y. For them, so nearly as I can tell, it means that you think about it while playing, but don’t and generally shouldn’t try to make the game more like it.I guess that depends on whether or not Gygax wanted the vibe of his game to match what happened in a standard Fafhrd and Grey Mouser story.
Oh yes, a bit before my time but I remember reading about that!Spectres were the Nazgul and until 5e were more powerful than wraiths.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.