Then I really should get busy finishing my read of Out of the Abyss since I'm spending all of this capital (or time, anyway) on the demon lords.
Unlike Orcus, who gets a pass because Tome of Horrors made him open content, Demogorgon is merely a name mythologically, and the two-headed, mandril and reptile hybrid with tentacles for arms incarnation of Demogorgon, who's semi-aquatic and semi-jungle, and who creates retrievers and death knights, etc. is a very specific D&D thing that can only be used in the way that a character owned by someone else can be used. So, he's good for your games. You can probably write fan fiction about him (although... please think twice before you do.) But if you want to write or publish something, you can't use him as is, really—unless it's at best a very oblique reference.
That said, I like Demogorgon a lot; maybe even more than Orcus, although it's a toss-up between the two of them, honestly. So, if I just did yesterday's post on Orcus, I probably need to do the same for Demogorgon.
This time, let's start off with the 1e incarnation of the big guy, up there in the corner. Twin mandrill heads, scaly tentacles for arms, and a lizardlike sinuous (albeit furry) body make up the gist of it. The art, as always for back then, was pretty poor, yet strangely evocative. (Note: an even more primitive illustration of him came out in Eldritch Wizardry, but since most players are more familiar with him from the Monster Manual, I'll start there. Besides; that art is really bad.) A better version of him came out in the Official AD&D Coloring Book.
Due to the strange way in which I was exposed to D&D, this is actually where I found him first. Those demons playing dice are supposed to be grog-demons, whatever they are, although I don't know what the little guy is. And it's funny that they're just sitting around gambling for some gold coins. The description here, written by Gygax himself is as follows: "Above all towers the twin madrill (sic) heads of Demogorgon, Prince of Demons. His blazing red eyes seem to transfix the horrified dwarf. Demogorgon's bristling green pelt and pink-suckered tentacles fill the viewer with such revulsion that he cries out and faints."
Like all of the demon lords, he skipped 2e entirely, and when he first made his 3e appearance in The Book of Vile Darkness, he'd somehow been given hyena heads, was green and even more serpentlike (although I've got that art kicking around somewhere, I'm not going to post it.) Although that's more funny than anything else, the fact remains that that book was kind of a trainwreck anyway. 3e in general wasted no time in getting the Prince of Demons, the Sibilant Beast, etc. back in the game. I've got a lot of artwork from that era. Steve Prescott did one of the first, and it's very classic.
It's curious that the really classic notion of what Demogorgon looked like was shaken by the hyena heads, I think. Although it didn't happen right away, we got a lot of differing interpretations of him, especially by the time 5e rolled around.
In any case, here's some more 3rd era art, most of which came out at the end of the era.
This was, I believe, actually a screenshot of some animation commissioned for some 4e preview stuff. Although when Demogorgon was actually finally statted in 4e (in Monster Manual 2) he looked a bit different.
His illustration from the Fiendish Codex. There's also some weird black and white sketches of him fighting Orcus, but he looks about like this. It's Orcus that looks weird.
This piece really reestablished his snakey, reptilian nature; but I don't think this look ever "stuck."
Near the very end of the 3e run, Demogorgon appeared (illustrated by the always illustrious WAR) on the cover of Dungeon and as a "final" boss in the Savage Tide adventure path.
At about that same time, he appeared on the cover of Dragon as part of the Demonomicon of Iggwilv series of articles.
These two pieces, on the other hand, give us the classic 4e look of Demogorgon, a bright orange monkey fellow who's somehow both very classic and yet newly imagined at the same time.
I've also got some other art that I don't know where it originally appeared. It may not even be official at all But here it is anyway.
Not meant to be an illustration of Demogorgon himself, but an interesting stylized piece nonetheless.
Another extraordinarily snakey-looking demogorgon, although those scales look more like overlapping armor plates than anything reptilian.
Finally, for 5e, he got a new look again. The mandrill heads might still be baboonish, but they look flensed of flesh if they are, and in some illustrations they just don't look baboon-like at all anyway. Lava-like light glows in his eyes, mouth, and even in cracks on his body. It's a very weird and demonic look, although it does by necessity, differ from what came before in some ways. He's also way bigger, and in at least one illustration, really bulky and squat rather than lithe and sinuous.
Finally, here's some stuff I've found recently, which kind of splits the difference between the 5e look and the more classic look as illustrated in 3e and 4e eras. It also comes in multiple color schemes, for whatever that's worth. The black-faced reddish one is probably my favorite. Although I admit by that point that I'm favoring a look that's more 5e than earlier. One of the greenish ones probably best matches Gygax's written description. I already wrote his coloring book text, but here's the description from the 1e Monster Manual: "It is contended by some that this demon prince is supreme, and in any event he is awesome in his power. This gigantic demon is 18' tall and reptilian. Demogorgon has two heads which bear the visages of evil baboons or perhaps mandrills with the hideous coloration of the latter named beasts. [ed note: It's worth pointing that a mandrill is a type of baboon, not a separate creature from baboons.] His blue-green skin is plated with snake-like scales, his body and legs are those of a giant lizard, his twin necks resemble snakes, and his thick tail is forked. Rather than having arms, he has great tentacles. His appearance testifies to his command of cold-blooded things such as serpents, reptiles, and octopi." His earlier description in Eldritch Wizardry is very similar; it's clear Gygax actually copied most of his earlier text.
The best write-up of Demogorgon occurs in Dragon 357 (with the cover art several illustrations above, as noted) and the best write-up of his abyssal layer is in Fiendish Codex I. He's statted there as a CR 33 threat. In the 5e book, Out of the Abyss, he's CR 26, although clearly the CRs aren't meant to correlate exactly. In the Fiendish Codex I, he's only CR 23.
Of course, I have no idea what he'd be in 1e, since they don't do CRs, but he's a bad mama-jamma, no doubt, in that game.