the Jester
Legend
I'd probably go with a basilisk, medusa or gorgon. OTOH advancing monsters in 3e (while sometimes a bit painful at the upper levels) is pretty easy stuff with fairly low-level, non-classed, non-templated advancement. A couple of other posters have already suggested some resources for churning them out or books to pull 'em from.
I'm glad you're enough of an expert in Gygax's life and mentality to make these claims.
Thanks for your valuable contribution to the thread.
BTW, what would you call pegasi if you were creating the first fantasy rpg? Skyflying horsebirds?
I call shenanigans on Gygax, apart from the "Why not" bit, which I think summed it up. Once you've met a creature and/or you've seen its description in the Monster Manual, you know what it freakin' is; it's no use pretending that you've done some sort of service to role-playing by bastardising legends so people don't know what they're fighting the very first time they encounter it. There was no good reason at all to call every winged horse "a Pegasus", or every snake-haired lady "a Medusa" other than possibly a lack of imagination and publication deadlines. Or watching too many of the cheesy Jason and the [Whatever] movies.
Maybe the lure to the ego of subverting classical mythology in the minds of tens of thousands of teenagers was just too much to pass up. Gygax was to mythology what Hollywood is to World War II...
I'm glad you're enough of an expert in Gygax's life and mentality to make these claims.

BTW, what would you call pegasi if you were creating the first fantasy rpg? Skyflying horsebirds?