Analysis of Monster Changes

In general, monster hit dice have been converted in a straightforward manner: from (AD&D1) some number of 8-sided dice plus a unique hp bonus, to (D&D3) some number of varying dice (see below) plus standard CON bonus. This generally makes for a larger bonus and hence, more hit points.

Obvious results from my analysis are that: (1) the number of hit dice for any monster is usually identical, and (2) armor class has stayed very close to the same (under the 20-AC conversion). However, hit dice have been improved for a number of great monster-types, like dragons, giants, demons, and so forth. Furthermore, the added Constitution hit point bonuses (and die type changes) have caused large hit point increases. Monster hit points have increased an average of +117% -- or about +55% when ignoring the greater monsters that have had HD increases. (Notably, the average Elf lost -40% hit points: going from 5 to 3 hp, they are one of the very few monsters to lose hit points.)

AD&D 1st Edition dragons have basically the same hit dice as "very young" dragons in D&D 3rd Edition (age category #2 out of 12; 6-15 years old). An AD&D1 "ancient" dragon, +55% hp, equals a D&D3 "young" dragon.

Many of these changes were first instituted as part of AD&D 2nd Edition power-inflation. Giants and demons have basically the same HD and AC as in AD&D2. Golems have the same HD as in AD&D2, but improved ACs. Dragons follow the same general advancement as in AD&D2, but HD and AC have again been improved (nearly doubling for the oldest).

Finally, some significant monster-types are at first glance missing entirely from the D&D3 Monster Manual, including the following: men (i.e., standard group types); green slime; most dinosaurs; prehistoric animals (baletchetherium, mammoth, etc.); modrons; daemons; arch-type demons, devils, slaad, etc.; githyanki/zerai.

Some of the preceding may be found in other official rulebooks. Men (and groups thereof) are given guidelines in the DMG (p. 135), while stats for 1st-level human warriors ("typical bandits or soldiers") are given in the Player's Handbook 2000 Survival Kit (p. 9). Green slime, along with yellow and brown mold, is also in the DMG (p. 117). Githyanki and githzerai appear in both the Psionics Handbook and the Manual of the Planes. Daemons are present in the Manual of the Planes, under the name "yugoloth" (as per 2nd Ed. parlance). Arch-devils and demon lords are detailed in the Book of Vile Darkness. Modrons have been presented in an online enhancement at wizards.com (at www.wizards.com/dnd/article.asp?x=dnd/we/we20010921a).

A late note on yugoloths/daemons: these are one of the few monster types to lose significant power in the conversion from AD&D to D&D 3^rd Edition. In AD&D, they were truly fearsome creatures: mezzodaemons had hit dice of 10d8+40 (85 hp), nycadaemons 12d8+36 (90 hp). They're disadvantaged because their rare pre-existing hit point bonuses weren't given any lift from 3^rd Edition Con adjustments, and they even lose base hit dice to boot. Instead of the average +55% hit point increase, mezzoloths lose almost half their hit points (8d8+8, 44 hp), and nycaloths go down as well (11d8+33, 82 hp). To retain their power level, these creatures would need some advancement, say for mezzodaemons to 15d8+60 (127 hp, Con 19, CR 13) and nycadaemons to 18d8+54 (135 hp, Con 17, CR 17).

Appendix

To view an Excel spreadsheet of standard D&D monsters, comparing them between 1st and 3rd Edition, see here.