When it comes to Warforged outside of Eberron, I try and justify them to DMs by saying "They're an ancient race created by a long-dead empire, and now have their own monastic societies." For some reason, having WF being meditative old guys just works for me.
Originally Posted by Yora
But the D&D monster is almost taken straight from a mythical sorcerer from Russia. Koschei the Deathless has been portrayed in images as an incredibly old man who looks almost like a walking skeleton, and he is some kind of sorcerer, and also immortal because he has a phylactery exactly as the D&D monster.
Koschei was also described in Frazer's The Golden Bough, which is still one of the ultimate introductory works on mythology. And I think Gygax even included it in some "Further Reading" lists in the back of some of his D&D books.
Koschei was also the inspiration for the Demon Lord Kostechtk... Kostiktok... Koosalagoopagoop... The Demon Lord who's a Frost Giant with a bigass club.