From the 2e MCA:
Some unique animals and giant animals, like 5-foot-tall kingfishers and ice bears, which are smarter than your average bear. Also Krynnish centaurs, lizardmen, minotaurs, and ogres. Even back then, I wondered why they needed to make new MC entries for them instead of just using the old entries and talking about the setting-specific differences elsewhere. Also, death knights and draconians.
Undead beasts: undead siege engines, not zombie animals. They're 20 feet tall.
Disir: gooey humanoids that pick up trash in their slime and like to attack and eat people, because they're evil.
Unique dragons: amphis, which are basically long-necked dragon turtles (evil); astral dragons, which are pretty small until they form a mated pair, at which point they become ginormous and are permanently connected by a far-too-short chain the gods make them wear to show their devotion, way to go Krynnish gods (neutral); ko dragons, which are sort of like furry, marsupial pseudodragons but smarter and capable of teleportation (neutral); sea dragons, which look like winged frogs (evil); and tylors, which are wingless and the result of a dragon mating with a hatori.
Dreamshadows and dreamwraiths: both are proto-templates, as almost every part of their statblock is "as person mimicked." Kind of pointless unless you want to mess with someone's dreams. Dreamwraiths are evil, dreamshadows are whatever alignment the person mimicked was.
Eyewings: fun little demons that look like winged tribbles with one giant eye that weeps homing drops of poison. Evil.
Fetches: demons that really should be a more standard D&D monster. Will pull you into the Abyss through its mirror. Evil.
Fire Minions: basically knight-shaped fire elementals. Evil.
Fireshadows: demons that are kind of encased in green flame and can turn people into green flame. Evil.
Gurik Cha'al: atomic horror-style mutated goblins. Evil.
Hatori: sand-swimming crocodiles. Chaotic Neutral, Low Intelligence--remember, dragons routinely mate with these things to create taylors.
Knight Haunt: basically floating armor; there's an invisible spirit in there. Good.
Horax: pack-hunting armored giant centipedes. Animal-unaligned.
Blood Sea Imp: As per normal imps, but from a specific location. Evil.
Kalothagh: giant pufferfish. No idea if anyone makes kalothagh sushi. Has an Int of 5-7. Neutral.
Kani Doll: An animated folk doll/figurine thing. Evil.
Kyrie: Like aarakocra, if aarakocra had human faces. Neutral.
Irda: high ogres. Neutral or Good.
Phaethon: fire-winged half-elves that I'm sure would get a lot of NSFW fanart on DeviantArt. Neutral.
Shadowpeople: basically the hadozee, if the hadozee lived underground and could create psychic thought-forms who ruled them. Neutral or Good.
Skrit: giant flightless beetles with dome-shaped elytra. Animal--unaligned
Spectral Minions: ghosts, except the only way they can harm anyone is if they died holding weapons. I'm not studying the entry so I don't know who they're minions of. Some of 'em are philosophers. Alignment depends on job.
Taylings and Taylands: creatures always born as psychically-bonded twins, with NG elf-like taylings and CN ogre-like taylands. Obviously a trap monster because a big ogre attacks you because CN and you kill it, only to discover you've harmed it's non-monstrous twin. Oh noes!
Thanoi: walrus men. Chaotic Evil, because of course they are.
Warrior Skeletons: Less cool death knights. Evil.
Witchlin: elven undead that look like a pair of skeletal hands and a pair of eyeballs. As if two of the bosses in Terraria had a kid. Evil.
Wyndlass: flying spiky swamp octopuses. Neutral.
Yaggol: degenerate mind flayers. They're shown wearing standard mind flayer outfits, you know, with the big collars and all, but they have Int 6 and the only psychic power they have is mind blast. Evil, even though it can barely tie its own shoes.
Saqualaminoi: Sasquatch. Neutral.