The errata on this page is very incomplete because the errata for True20 Adventure Roleplaying and True20 Bestiary were being maintained by True20 editor and contributor Erica Balsley on her website, which no longer exists. The only other source of collected errata that I have found is the following archived and locked thread in the True20 Forum (to which I contributed when the thread was still active, and from which Erica derived much of her material): http://roninarmy.com/true20-forum-archive/viewtopic.php?f=2&t=360
The errata below consist of new errata that I have discovered (or rediscovered?) since learning of that site's loss. I have also included two lists from my previous errata site: an index of monsters by type, and a list of MM monsters not found in the True20 Bestiary.
New True20 Bestiary Errata
p. 47, Crocodile: The MM crocodile is Medium, with the same ability scores. However, they are also described as 11-12 feet long, which would normally make them Large.
Monsters by Type (and Subtype)
Creatures from True20 Adventure Roleplaying are also indexed here, and marked by "[core]" or by the setting chapter title.
The handful of new creatures in the True20 Companion and True20 Narrator's Kit are indexed here rather than given their own page.
Aberration: avatar of decay, cloaker, destrachan, ettercap, flesh freak, jade eviscerator, mimic, naga, otyugh, rust monster, will-o'-wisp
(Air): cloud giant, electrohydra, sky dragon, will-o'-wisp
Animal: ape, baboon, badger, bat [core], bat swarm, bear [core], bison, boar [core], camel, cat [core], cheetah, crocodile, deer [core], dinosaur, dire animal, dire rat [core], dog [+core], donkey, eagle, elephant, ferret, fox, hawk [core], horse [core], hyena, leopard, liger, lion, lizard, lynx, manta ray, monkey, moose, mule, octopus, owl, pony, porpoise, rat [core], rat swarm, raven, rhinoceros, roc, shark [core], snake [+core], squid, tiger, toad, weasel, whale, wolf [core], wolverine
(Aquatic): aquatic elf, bear-shark [core], dragon turtle, kraken, locathah, manta ray, merfolk, nixie, octopus, sahaugin, shark [core], shell golem, squid
(Cold): cryohydra, crypt wight [core], frost giant, frost worm, ice dragon, moon dragon, wendigo, winter wolf
Construct: animated armor, church grotesque, clockwork creature, golem, homonculus, juggernaut, manned vehicle [Companion], retriever, sentry robot [Narrator's Kit], simulacrum, synthetic [Lux Aeternum]
Dragon: dragon [+core], dragon turtle, drake, half-dragon, pseudodragon, wyvern
(Earth): cave troll, cyclops, forest dragon, mountain dragon [+core], mountain troll, stone giant, true gargoyle
Elemental: aether elemental, void elemental
Elemental (Air): air elemental, force of nature, invisible stalker
Elemental (Earth): earth elemental, force of nature
Elemental (Fire): fire elemental, force of nature
Elemental (Water): water elemental, force of nature
Fey: dryad, faun [Companion], green knight, jacklova, nymph, satyr, sprite, wendigo
(Fire): fire dragon, fire giant, jacklova, phoenix, pyrohydra, sun dragon
(Giant): cyclops, ettin, giant, great goblin, morphean, ogre [core], ogre mage, troll
(Goblinoid): bugbear, goblin [core], great goblin, hobgoblin
Humanoid: anthropomorphic animal [Companion], black orc, bugbear, caliban [core], cyclops, doppelganger, draugmorre [?; Lux Aeternum], dwarf [+core], elf [+core, + Companion], ettin, giant, gnoll, gnome [+core], goblin [core], great goblin, grey orc, halfling [+core], half-orc [core], hobgoblin, human [+core, + Companion], kobold, kyryk [?; Lux Aeternum], lizardfolk, locathah, lycanthrope, mercenary orc company, merfolk, morphean, mutated crewmember [Narrator's Kit], necrite, ogre [core], ogre mage, orc [core], otterfolk, troglodyte, troll, v'la [?; Lux Aeternum]
(Incorporeal): aether elemental, allip, apparition, ghost [core], void elemental, shadow, spectre, wraith
Kaiju: kaiju [Mecha vs. Kaiju]
Monstrous Humanoid: centaur [+ Companion], derro, gorlack, grimlock, hag, harpy [core], kamodon [core], medusa, minotaur, sahaugin,
true gargoyle
Ooze: blood pudding [core], ooze
Outsider: angel of death, chronicler of time, couatl, djinn [Caliphate Nights], guardian angel, half-fiend, janni, planetouched, praetor of souls, rakshasa, shadow mastiff, titan, watcher in the sky
Outsider (Air): belker, djinni
Outsider (Earth): thoqqua, xorn
Outsider (Fire): azer, efreeti, hell hound, salamander, thoqqua
Outsider (Vice): fiend [all but retriever], hell hound, yeth hound
Outsider (Virtue): celestial [all but angels?], night hag, nightmare
Outsider (Water): triton
Plant: assassin vine, foot-trap, fungus, gideon fungi, pit plant, shambling mound, tendriculos, treant
(Reptilian): draugmorre [?; Lux Aeternum], kamodon [core], kobold, lizardfolk, troglodyte
(Shapechanger): doppelganger, imp, lycanthrope, mimic, moon dragon, quasit, succubus/incubus, sun dragon, wendigo
Supernatural Beast: ankheg, basilisk, bear-shark [core], behemoth, behir, blink dog, bulette, celestial creature (animal or vermin), chimera, cockatrice, darkmantle, dragonne, fiendish creature (animal or vermin), frost worm, giant eagle, giant owl, gorgon, griffon, hellwasp swarm, hippogriff, hydra, kraken, lamia, lammasu, magic deer [core], manticore, owlbear, pegasus, phoenix, purple worm, questing beast, remorhaz, roper, shocker lizard, sphinx, spirit-horse, stirge, thunder bird, unicorn, winter wolf, worg
(Swarm): swarm [+core]
Undead: allip, apparition, bodak, corpse-stitched abomination, crypt wight [core], draug, ghost [core], ghoul, lich, mummy, shadow, skeleton [+core], spectre, vampire [+core], wight, wraith, zombie [+core]
Vermin: ant, ant lion, bee, beetle, carpenter caterpillar, centipede, centipede swarm, cockroach [core], dragonfly, killer bee swarm [core], locust swarm, maggot swarm, mosquito, praying mantis, scorpion, spider, spider swarm, termite, wasp
(Vice): church grotesque, hellwasp swarm
(Virtue): [none]
(Water): swamp dragon
The True20 Bestiary and the Monster Manual
Most creatures from the d20 Monster Manual were converted to True20 in either True20 Adventure Roleplaying or the True20 Bestiary. A list of those that were not follows.
"[non-OGL]" means the creature is not Open Game Content (see Non-OGL MM Creatures).
Aboleth
Achaierai [see Dark Wings Over Freeport]
Animated Object
Aranea [see the True20 Freeport Companion]
Arrowhawk
Athach
Barghest
Bear, Black
Bear, Polar [use advanced Bear?]
Beholder [non-OGL]
Beholder, Gauth [non-OGL]
Carrion Crawler [non-OGL]
Chaos Beast
Choker
Chuul
Delver
Devourer
Digester
Displacer Beast [non-OGL]
Dragon, True (Brass Dragon, Bronze Dragon, Copper Dragon)
Drider
Eladrin (Bralani, Ghaele)
Elemental (all Greater and Elder) [use advanced Huge elementals]
Ethereal Filcher
Ethereal Marauder
Formian
Gibbering Mouther
Girallon
Githyanki [non-OGL]
Githzerai [non-OGL]
Golem, Flesh [but see Corpse-Stitched Abomination?]
Gray Render
Grick
Guardinal (Avoral, Leonal)
Howler
Inevitable (Kolyarut, Marut, Zelekhut)
Krenshar
Kuo-Toa [non-OGL]
Lycanthrope (Hill Giant Dire Wereboar)
Magmin
Mephit (Air, Dust, Earth, Fire, Ice, Magma, Ooze, Salt, Steam, Water)
Mind Flayer [non-OGL]
Mohrg
Nightshade (Nightcrawler, Nightwalker, Nightwing)
Phantom Fungus
Phase Spider
Phasm
Rast
Ravid
Sea Cat
Shark (Large, Huge)
Shield Guardian
Skum
Slaad [non-OGL]
Spider-Eater
Tarrasque
Tojanida
Umber Hulk [non-OGL]
Vampire Spawn [use Vampire template instead]
Vargouille
Xill
Yrthak
Yuan-ti [non-OGL]