In the Bible, Gog and Magog (or Gog from Magog depending on how you translate it) are personifications of what academics term "The Other." The different (barbaric) culture that threatens "our" culture. They were leaders of a faraway land (or Gog was the leader of the faraway land of Magog), and their barbarous hordes would come and sack the Holy Land in the End Times.
The Biblical Gog and Magog were co-opted by Geoffrey of Monmouth in his History of the Kings of Britain [also possibly just adjusting the Welsh/Breton name of Gawr Madoc to a more familiar name for his audience]. They were combined into a giant named Gogmagog, or Goemagog. This giant, and a bunch of his kin, attacked Brutus, Geoffrey's first king of Britain and a refugee from the fall of Troy. Corineus, the follower of Brutus who was granted Cornwall as his province, wrestled with Gogmagog and eventually threw him into the sea.
Going off Geoffrey, but using a bit of the Biblical idea of Gog and Magog as beastial outsider barbarians, I present Gogmagog giants for D&D:
AC: 3 (17)
Move: 120 (40)
Attacks: 1 club
No. Appearing: 1-4 (2-8)
Save As: F9
Treasure Type: G
Appearing to be 18 foot tall Orcs, Gogmagog giants are wild and ferocious giants who inhabit the most desolate of regions far from the realms of men. They tend to fight with tree trunks which they rip from the ground and use as clubs. Anyone hit by a Gogmagog's club must Save vs. Wands or be knocked back 10 feet for each point of damage dealt (no additional damage for the knockback, unless it results in a collision or fall). They rarely throw rocks, and when they do throw them with ranges 40/80/120, for the standard 3d6 damage. Gogmagog giants are often leaders of mixed bands of giants and humanoids, at least when they are on a raid. In their crude settlements, other more intelligent or persuasive members tend to manipulate the less intelligent Gogmagogs.