D&D Monsters: Frost and Fire Giants

Both frost and fire giants, as portrayed in D&D, are loosely based on the jötunn of Norse myth. In the original myths, this was a rather vague term referring to a race of mostly (but not always) gigantic beings originally created by the primordial being Ymir. Ymir himself was certainly gigantic, since the sky is said to be the inside of his blue-coloured skull, and he was also described in the Prose Edda as "ice cold". Thus, while frost giants aren't a specific thing in Norse myth, it's clear where the idea comes from. Fire giants, apparently also descended from Ymir in the original myth, are the inhabitants of the fiery realm of Muspelheim, led by Surtur, whose primary function in the myths is to destroy the world at the conclusion of Ragnarok.

Both frost and fire giants appear in a range of fictional sources, of which perhaps the most obvious are the Mighty Thor comics. These predate D&D by over ten years, although it's likely that their appearance in the game is an independent creation from the same mythic origin, since they're quite clearly different from the comicbook versions. In D&D, they are the third and fourth rungs on the six-step ladder of increasing giant power and strength and are portrayed as more technologically advanced than the smaller hill and stone giants.

D&D Monsters: Hill and Stone Giants

Giants are a recurring figure in myth and folklore, appearing in the stories of just about every real-world culture. There's something fundamental about the idea of people who look vaguely like us but are much larger and stronger. There is, of course, considerable variation among cultures as to what giants are supposed to be like, and even D&D reflects this by having six different core types, even before we get into one-mention specials or other creatures that are, in some sense, gigantic humanoids (such as ogres).

As is common where variants of the same idea for a monster exist in 1E, the six basic giants are arranged in a clear hierarchy of power, with each type having one extra hit dice, one extra point of strength, and delivering one extra die of damage than the one below it. Unlike some other creatures, while the details change, this progression of power remains the same in later editions.