Quote Originally Posted by Particle_Man View Post
In fact, didn't OD&D only have 5 alignments? LG, CE, CG, LE and N?
Not exactly. Originally there was just Law, Neutrality, and Chaos, inherited from Chainmail. Gygax, in articles in Strategic Review and Dragon Magazine, added Good and Evil, so you had Good, Evil, Law, Chaos, and Neutrality; he didn't have the combined alignments, but he did lay out planes for those slots in the grid (and interestingly Elysium was originally the CG plane, with "Paradise" taking the NG slot). Holmes Basic D&D switched it up to LG, CG, LE, CE, and N with no neutrals, and BECMI went back to just L/N/C as AD&D codified all nine alignments.

It explains why even now we still have pages and pages for Devils and Demons, not as much for Yugoloths (or other NE extraplanars). LN has modrons and formians and . . . I don't even know. CN has slaads and . . . I don't even know. NG has animal people, because why the heck not.
I think the reason yugoloths are less detailed is that (A) demons and devils came in with the AD&D MM but "daemons" (as they were called then) were introduced in adventure modules and the Fiend Folio and (B) devils and demons got plenty of flavor attention in the main books but yugoloths were really only fleshed out in Planescape, so there's less material to draw on and less of a legacy to work with.

LN has inevitables as of 3e (technically 1e, since the marut showed up then, but it was a one-off monster rather than part of a larger category), CN has nothing else by design, and NG most likely goes with the animal-headed creature theme because the Good exemplar races draw from the good gods in mythology, and Egyptian-/Greek-/Celtic-style "people with animal heads" gods fit in nicely with the archons' Judeo-Christian "wings and glowy lights" aesthetic and the eladrins' "super-elf nature gods" look.