Of all the D&D projects I've worked on, the third edition
Fiend Folio still stands out as one of the most interesting. For starters, four of the seven designers on the book worked in the Wizards of the Coast periodicals department, so there was a lot of friendly creative competition that resulted in a much stronger product in the long run. Plus, the creative side of the book's management fell to
James Wyatt, who is one of the nicest professionals in the industry and a great guy to work with.
But the thing that made the book truly special was the competition to create the next githyanki. Introduced to geekdom in the first edition
Fiend Folio, the githyanki were a race of evil humans enslaved by squid-faced aliens called mind flayers (a "staple" creature revealed in the previously published
Monster Manual, among other sources). Eventually, these creatures developed psionic powers and broke the bonds of their enslavement. Thereafter, they moved to the Astral Plane and spent most of their days battling a racial offshoot, the githzerai.
Both the githyanki and the githzerai were created by
Charles Stross, who also created the infamous slaads and the inimitable death knight and who later went on to garner Hugo and Nebula nominations for his science-fiction writing.
The githyanki were unlike most of the monsters in the original
Fiend Folio in that they were connected to other elements of the "D&D universe," a trait common to all of the Charlie Stross monsters in the book. They were imaginative and came with a compelling backstory.
But principally the githyanki's popularity came from the fact that they looked like this:

So when James Wyatt sent out the email that gave us our marching orders on the third edition
Fiend Folio, he included an enticing challenge. In addition to the conversions of old monsters and the new creatures we were asked to design ("CR 10 aberration"), we each received an additional assignment:
Design something as cool and as potentially long-lasting as the githyanki.
We referred to these creatures as our "gith candidates." It wasn't clear, at the time of the assignment, that all of these would be accepted and published in the final book. Designing the coolest "gith candidate" became something of a contest in periodicals. All seven of us received a different creature type. I jumped at the chance to design a compelling aberration, reasoning that the more unusual the creature could be, the more people would like it. Each of us had our own criteria for what we wanted to include in our gith candidate, but I started off with a list that went something like this:
• Make it look human enough so people will identify with it.
• Give it interesting powers and tie it into the D&D universe.
• Make it tough enough that people will remember it.
At the end of the process, I came up with a gith candidate I thought just might click. My secret goal was to make my gith candidate better than everyone else's—at this point it wasn't at all clear that all of them would make it into the book, and the only way I could ensure my candidate's inclusion was to make him cooler than the rest of them.
I went so far as to ask my friend
Kyle Hunter to sketch out some ideas for me, which I forwarded along with my detailed write-up. Here's what we came up with:

I named my creatures the "
ethergaunts," and described them as an advanced culture that abandoned the Material Plane for the Ethereal Plane, and who were now in the process of "coming home" after 10,000 years, only to discover that their old domain was now infested with mortal creatures they considered no more relevant than insects.
"Ethergaunts communicate with each other by wriggling their head tendrils, which transmits a psychic 'soundprint' identifiable as language to other ethergaunts within normal hearing range. They occasionally communicate with members of Material Plane races by revealing their true faces to one of the creature's cohorts and using that dominated ally as a psychic puppet-envoy."
In retrospect, I've always thought the ethergaunts were a little too esoteric to win the Battle of the Gith Candidates. With a few years of hindsight, I think it's fair to say that
James Jacobs's kaorti probably won that competition in a landslide, followed by
Jesse Decker's shadar-kai. The ethergaunts probably fall somewhere in the middle of the pack.
Which is why I was stunned, this evening, to find a
20,620-word essay on the ethergaunts posted to a prominent Dungeons & Dragons messageboard. Here I thought the poor ethergaunts were essentially unloved, only to find out that someone out there has written about five times more material on them than I have.
I haven't had time to digest the entire series of posts, yet, but it looks very creative and quite interesting. As the father of the ethergaunts, I'm pleased that my gith candidate stoked the fires of at least one gamer's over-active imagination.
For what it's worth, here are the other
Fiend Folio creatures I designed:
• Century Worm
• Deva, Monadic
• Deva, Movanic
• Imp, Bloodbag
• Imp, Euphoric
• Imp, Filth
• Phiuhl
• Shedu
• Yellow Musk Creeper
• Yellow Musk Creeper Template
I remember being very excited at the time to get a chance to update and re-interpret a lot of "classic" D&D monsters, but in retrospect I think I would have preferred writing more completely original creatures.